ui: fix problemId display

packages/ui-default/templates/components/problem.html

@@ -8,7 +8,7 @@
 {%- if tdoc and alphabetic -%}
   <b>{{ String.fromCharCode(65 + tdoc.pids.indexOf(pdoc.docId)) if tdoc.pids.includes(pdoc.docId) else '#' }}</b>
 {%- else -%}
-  <b>{{ pdoc.pid.split('-')[1] if pdoc.pid else ('P'+pdoc.docId) }}</b>
+  <b>{{ (pdoc.pid.split('-')[1] if pdoc.pid.includes('-') else pdoc.pid) if pdoc.pid else ('P'+pdoc.docId) }}</b>
 {%- endif -%}
 {%- if not small -%}&nbsp;&nbsp;{{ pdoc.title }}{%- endif -%}
 {%- if not invalid -%}