Fix statistics evaluation when category has non-trivial offset.

Author: lukaskogaborik

bullet/problems/logic/stats.py

@@ -52,7 +52,7 @@ def generate_stats_category(category: Category):
     stats = []
     for team in teams:
         for number, received in receive_times[team.id].items():
-            if number > len(problems) + first_problem - 1:
+            if number > len(problems) - first_problem + 1:
                 continue
             solved = None
             if number in solve_times[team.id]: