diff --git a/csp/contests/unpriv_main_page.csp b/csp/contests/unpriv_main_page.csp
index c09850233..39428a417 100644
--- a/csp/contests/unpriv_main_page.csp
+++ b/csp/contests/unpriv_main_page.csp
@@ -16,6 +16,18 @@ ns_unparse_statement(
         const unsigned char *bb,
         int is_submittable);
 
+int
+compare_prob_with_start_date_name(const int * l, const int * r, const struct section_problem_data **probs) {
+    if (probs[*l]->start_date > probs[*r]->start_date) {
+        return -1;
+    }
+    if (probs[*l]->start_date < probs[*r]->start_date) {
+        return 1;
+    }
+    // qsort is unstable that why use id as stabilization
+    return *l - *r;
+}
+
 void
 ns_unparse_answers(
         FILE *fout,
@@ -278,11 +290,22 @@ ns_unparse_answers(
     // vertical navigation bar
 %></div></td><td class="b0" id="probNavRightList" valign="top"><%
     prev_group_name[0] = 0;
-
-    for (i = 1, j = 0; i <= cs->max_prob; i++) {
+    int probs = 0;
+    int indexes[cs->max_prob];
+    for (i = 1; i <= cs->max_prob; i++) {
       if (!(prob = cs->probs[i])) continue;
       if (!(pinfo[i].status & PROB_STATUS_TABABLE)) continue;
+      indexes[probs] = i;
+      ++probs;
+    }
+    if (global->vertical_navigation_sdate_sort > 0) {
+      qsort_r(indexes, probs, sizeof(indexes[0]), compare_prob_with_start_date_name, cs->probs);
+    }
 
+    for (j = 0; j < probs; ++j) {
+      i = indexes[j];
+      if (!(prob = cs->probs[i])) continue;
+      if (!(pinfo[i].status & PROB_STATUS_TABABLE)) continue;
       if (prob->group_name && strcmp(prob->group_name, prev_group_name)) {
 %><div class="probDisabled"><s:v value="prob->group_name" escape="false" /></div><%
         snprintf(prev_group_name, sizeof(prev_group_name), "%s", prob->group_name);
@@ -303,7 +326,6 @@ ns_unparse_answers(
       }
 %><s:url name="ProblemUrl" ac="view-problem-submit"><s:param name="prob_id" value="i" /></s:url><%
 %><s:a class="tab" url="ProblemUrl"><s:v value="prob->short_name" escape="false" /></s:a></div><%
-      j++;
     }
 %></td></tr></table>
 <%
diff --git a/csp/super-server/cnts_edit_cur_global_page.csp b/csp/super-server/cnts_edit_cur_global_page.csp
index 1dbe0f7a3..6c789189b 100644
--- a/csp/super-server/cnts_edit_cur_global_page.csp
+++ b/csp/super-server/cnts_edit_cur_global_page.csp
@@ -44,6 +44,7 @@ static const unsigned char MSG_disable_user_standings[] = "Disable build-in stan
 static const unsigned char MSG_disable_language[] = "Disable language column in new-client";
 static const unsigned char MSG_problem_navigation[] = "Advanced problem navigation";
 static const unsigned char MSG_vertical_navigation[] = "Place problem navigation vertically";
+static const unsigned char MSG_vertical_navigation_sdate_sort[] = "Sort problem navigation vertically with problem start_date descending";
 static const unsigned char MSG_disable_virtual_start[] = "Disable user Virtual start button";
 static const unsigned char MSG_disable_virtual_auto_judge[] = "Disable auto-judging after virtual olympiad";
 static const unsigned char MSG_enable_auto_print_protocol[] = "Enable automatic protocol printing";
@@ -328,6 +329,7 @@ static const unsigned char * const form_row_attrs[]=
         <%@expand EDIT_BOOL_ROW "disable_language" "caps" "400px" %>
         <%@expand EDIT_BOOL_ROW "problem_navigation" "caps" "400px" %>
         <%@expand EDIT_BOOL_ROW "vertical_navigation" "caps" "400px" %>
+        <%@expand EDIT_BOOL_ROW "vertical_navigation_sdate_sort" "caps" "400px" %>
         <%@expand EDIT_BOOL_ROW "disable_virtual_start" "caps" "400px" %>
         <%@expand EDIT_BOOL_ROW "disable_virtual_auto_judge" "caps" "400px" %>
         <%@expand EDIT_BOOL_ROW "enable_auto_print_protocol" "caps" "400px" %>
@@ -896,6 +898,7 @@ function popupCapsDialog(e, skipField)
         "disable_language",
         "problem_navigation",
         "vertical_navigation",
+        "vertical_navigation_sdate_sort",
         "disable_virtual_start",
         "disable_virtual_auto_judge",
         "enable_auto_print_protocol",
@@ -926,6 +929,7 @@ function capsDialogOnChange()
     $("#caps-disable_banner_page-div").toggle($("#caps-enable_printing").is(':checked'));
     $("#caps-printout_uses_login-div").toggle($("#caps-enable_printing").is(':checked') && $("#caps-disable_banner_page").is(':checked'));
     $("#caps-vertical_navigation-div").toggle($("#caps-problem_navigation").is(':checked'));
+    $("#caps-vertical_navigation_sdate_sort-div").toggle($("#caps-problem_navigation").is(':checked'));
     $("#caps-disable_virtual_start-div").toggle(<s:v type="jsbool" value="global->is_virtual > 0" />);
     $("#caps-disable_virtual_auto_judge-div").toggle(<s:v type="jsbool" value="global->score_system == SCORE_OLYMPIAD" />);
     $("#caps-enable_auto_print_protocol-div").toggle(<s:v type="jsbool" value="global->score_system == SCORE_OLYMPIAD" />);
@@ -1438,6 +1442,7 @@ function advancedDialogOnChange()
             <%@expand ORIG_BOOL_ROW "disable_language" %>
             <%@expand ORIG_BOOL_ROW "problem_navigation" %>
             <%@expand ORIG_BOOL_ROW "vertical_navigation" %>
+            <%@expand ORIG_BOOL_ROW "vertical_navigation_sdate_sort" %>
             <%@expand ORIG_BOOL_ROW "disable_virtual_start" %>
             <%@expand ORIG_BOOL_ROW "disable_virtual_auto_judge" %>
             <%@expand ORIG_BOOL_ROW "enable_auto_print_protocol" %>
diff --git a/csp/super-server/glob_save_capabilities_form.csp b/csp/super-server/glob_save_capabilities_form.csp
index 336f46f59..29775546f 100644
--- a/csp/super-server/glob_save_capabilities_form.csp
+++ b/csp/super-server/glob_save_capabilities_form.csp
@@ -35,6 +35,7 @@
     ejintbool_t disable_language = 0;
     ejintbool_t problem_navigation = 0;
     ejintbool_t vertical_navigation = 0;
+    ejintbool_t vertical_navigation_sdate_sort = 0;
     ejintbool_t disable_virtual_start = 0;
     ejintbool_t disable_virtual_auto_judge = 0;
     ejintbool_t enable_auto_print_protocol = 0;
@@ -72,6 +73,7 @@
 %><s:read var="disable_language" default="0" /><%
 %><s:read var="problem_navigation" default="0" /><%
 %><s:read var="vertical_navigation" default="0" /><%
+%><s:read var="vertical_navigation_sdate_sort" default="0" /><%
 %><s:read var="disable_virtual_start" default="0" /><%
 %><s:read var="disable_virtual_auto_judge" default="0" /><%
 %><s:read var="enable_auto_print_protocol" default="0" /><%
@@ -109,6 +111,7 @@
             global->disable_language = disable_language;
             global->problem_navigation = problem_navigation;
             global->vertical_navigation = vertical_navigation;
+            global->vertical_navigation_sdate_sort = vertical_navigation_sdate_sort;
             global->disable_virtual_start = disable_virtual_start;
             global->disable_virtual_auto_judge = disable_virtual_auto_judge;
             global->enable_auto_print_protocol = enable_auto_print_protocol;
diff --git a/gen/prepare_meta.c b/gen/prepare_meta.c
index 954ca8291..8ef08d479 100644
--- a/gen/prepare_meta.c
+++ b/gen/prepare_meta.c
@@ -66,6 +66,7 @@ static struct meta_info_item meta_info_section_global_data_data[] =
   [CNTSGLOB_problem_navigation] = { CNTSGLOB_problem_navigation, 'B', XSIZE(struct section_global_data, problem_navigation), "problem_navigation", XOFFSET(struct section_global_data, problem_navigation) },
   [CNTSGLOB_problem_tab_size] = { CNTSGLOB_problem_tab_size, 'i', XSIZE(struct section_global_data, problem_tab_size), "problem_tab_size", XOFFSET(struct section_global_data, problem_tab_size) },
   [CNTSGLOB_vertical_navigation] = { CNTSGLOB_vertical_navigation, 'B', XSIZE(struct section_global_data, vertical_navigation), "vertical_navigation", XOFFSET(struct section_global_data, vertical_navigation) },
+  [CNTSGLOB_vertical_navigation_sdate_sort] = { CNTSGLOB_vertical_navigation_sdate_sort, 'B', XSIZE(struct section_global_data, vertical_navigation_sdate_sort), "vertical_navigation_sdate_sort", XOFFSET(struct section_global_data, vertical_navigation_sdate_sort) },
   [CNTSGLOB_disable_virtual_start] = { CNTSGLOB_disable_virtual_start, 'B', XSIZE(struct section_global_data, disable_virtual_start), "disable_virtual_start", XOFFSET(struct section_global_data, disable_virtual_start) },
   [CNTSGLOB_disable_virtual_auto_judge] = { CNTSGLOB_disable_virtual_auto_judge, 'B', XSIZE(struct section_global_data, disable_virtual_auto_judge), "disable_virtual_auto_judge", XOFFSET(struct section_global_data, disable_virtual_auto_judge) },
   [CNTSGLOB_enable_auto_print_protocol] = { CNTSGLOB_enable_auto_print_protocol, 'B', XSIZE(struct section_global_data, enable_auto_print_protocol), "enable_auto_print_protocol", XOFFSET(struct section_global_data, enable_auto_print_protocol) },
diff --git a/include/ejudge/meta/prepare_meta.h b/include/ejudge/meta/prepare_meta.h
index f754cd600..01da39845 100644
--- a/include/ejudge/meta/prepare_meta.h
+++ b/include/ejudge/meta/prepare_meta.h
@@ -61,6 +61,7 @@ enum
   CNTSGLOB_problem_navigation,
   CNTSGLOB_problem_tab_size,
   CNTSGLOB_vertical_navigation,
+  CNTSGLOB_vertical_navigation_sdate_sort,
   CNTSGLOB_disable_virtual_start,
   CNTSGLOB_disable_virtual_auto_judge,
   CNTSGLOB_enable_auto_print_protocol,
diff --git a/include/ejudge/prepare.h b/include/ejudge/prepare.h
index 9cd1376ea..8250fcd38 100644
--- a/include/ejudge/prepare.h
+++ b/include/ejudge/prepare.h
@@ -264,6 +264,8 @@ struct section_global_data
   int problem_tab_size;
   /** display problem tabs vertically */
   ejintbool_t vertical_navigation;
+  /** use start_date sort order instead of problem id  */
+  ejintbool_t vertical_navigation_sdate_sort;
   /** disable "virtual start" command for contestants */
   ejintbool_t disable_virtual_start;
   /** disable auto-judging after virtual olympiad is finished for a user */
diff --git a/include/ejudge/prepare_dflt.h b/include/ejudge/prepare_dflt.h
index b73fda953..2569ae26d 100644
--- a/include/ejudge/prepare_dflt.h
+++ b/include/ejudge/prepare_dflt.h
@@ -114,6 +114,7 @@
 #define DFLT_G_DISABLE_LANGUAGE 0
 #define DFLT_G_PROBLEM_NAVIGATION 0
 #define DFLT_G_VERTICAL_NAVIGATION 0
+#define DFLT_G_VERTICAL_NAVIGATION_SDATE_SORT 0
 #define DFLT_G_DISABLE_VIRTUAL_START 0
 #define DFLT_G_DISABLE_VIRTUAL_AUTO_JUDGE 0
 #define DFLT_G_ENABLE_AUTO_PRINT_PROTOCOL 0
diff --git a/lib/prepare.c b/lib/prepare.c
index 6fa009631..c299dfacc 100644
--- a/lib/prepare.c
+++ b/lib/prepare.c
@@ -108,6 +108,7 @@ static const struct config_parse_info section_global_params[] =
   GLOBAL_PARAM(problem_navigation, "d"),
   GLOBAL_PARAM(problem_tab_size, "d"),
   GLOBAL_PARAM(vertical_navigation, "d"),
+  GLOBAL_PARAM(vertical_navigation_sdate_sort, "d"),
   GLOBAL_PARAM(disable_virtual_start, "d"),
   GLOBAL_PARAM(disable_virtual_auto_judge, "d"),
   GLOBAL_PARAM(enable_auto_print_protocol, "d"),
@@ -884,6 +885,7 @@ global_init_func(struct generic_section_config *gp)
   p->disable_language = -1;
   p->problem_navigation = -1;
   p->vertical_navigation = -1;
+  p->vertical_navigation_sdate_sort = -1;
   p->disable_virtual_start = -1;
   p->disable_virtual_auto_judge = -1;
   p->enable_auto_print_protocol = -1;
@@ -2826,6 +2828,8 @@ set_defaults(
     g->problem_navigation = DFLT_G_PROBLEM_NAVIGATION;
   if (g->vertical_navigation == -1)
     g->vertical_navigation = DFLT_G_VERTICAL_NAVIGATION;
+  if (g->vertical_navigation_sdate_sort == -1)
+    g->vertical_navigation_sdate_sort = DFLT_G_VERTICAL_NAVIGATION_SDATE_SORT;
   if (g->disable_virtual_start == -1)
     g->disable_virtual_start = DFLT_G_DISABLE_VIRTUAL_START;
   if (g->disable_virtual_auto_judge == -1)
@@ -5474,6 +5478,7 @@ prepare_set_global_defaults(
   if (g->disable_language < 0) g->disable_language = DFLT_G_DISABLE_LANGUAGE;
   if (g->problem_navigation < 0) g->problem_navigation = DFLT_G_PROBLEM_NAVIGATION;
   if (g->vertical_navigation < 0) g->vertical_navigation = DFLT_G_VERTICAL_NAVIGATION;
+  if (g->vertical_navigation_sdate_sort < 0) g->vertical_navigation_sdate_sort = DFLT_G_VERTICAL_NAVIGATION_SDATE_SORT;
   if (g->disable_virtual_start < 0) g->disable_virtual_start = DFLT_G_DISABLE_VIRTUAL_START;
   if (g->disable_virtual_auto_judge < 0) g->disable_virtual_auto_judge = DFLT_G_DISABLE_VIRTUAL_AUTO_JUDGE;
   if (g->enable_auto_print_protocol < 0) g->enable_auto_print_protocol = DFLT_G_ENABLE_AUTO_PRINT_PROTOCOL;
@@ -5758,6 +5763,7 @@ prepare_new_global_section(int contest_id, const unsigned char *root_dir,
   global->disable_language = DFLT_G_DISABLE_LANGUAGE;
   global->problem_navigation = 1;
   global->vertical_navigation = DFLT_G_VERTICAL_NAVIGATION;
+  global->vertical_navigation_sdate_sort = DFLT_G_VERTICAL_NAVIGATION_SDATE_SORT;
   global->disable_virtual_start = DFLT_G_DISABLE_VIRTUAL_START;
   global->disable_virtual_auto_judge = DFLT_G_DISABLE_VIRTUAL_AUTO_JUDGE;
   global->enable_auto_print_protocol = DFLT_G_ENABLE_AUTO_PRINT_PROTOCOL;
diff --git a/lib/prepare_out.c b/lib/prepare_out.c
index eb7513cc4..f05377991 100644
--- a/lib/prepare_out.c
+++ b/lib/prepare_out.c
@@ -266,6 +266,8 @@ prepare_unparse_global(
     unparse_bool(f, "problem_navigation", global->problem_navigation);
   if (global->vertical_navigation != DFLT_G_VERTICAL_NAVIGATION)
     unparse_bool(f, "vertical_navigation", global->vertical_navigation);
+  if (global->vertical_navigation_sdate_sort != DFLT_G_VERTICAL_NAVIGATION_SDATE_SORT)
+    unparse_bool(f, "vertical_navigation_sdate_sort", global->vertical_navigation_sdate_sort);
   if (global->disable_virtual_start != DFLT_G_DISABLE_VIRTUAL_START)
     unparse_bool(f, "disable_virtual_start", global->disable_virtual_start);
   if (global->disable_virtual_auto_judge != DFLT_G_DISABLE_VIRTUAL_AUTO_JUDGE)