/in/foo.cc: In function 'int main()':
/in/foo.cc:42:10: warning: iteration 100004 invokes undefined behavior [-Waggressive-loop-optimizations]
   fac[i] = fac[i - 1] * i % P;
   ~~~~~~~^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:37:19: note: within this loop
  for(int i = 1; i <= maxn; ++i) {
                 ~~^~~~~~~