/in/foo.cc: In function 'int main()':
/in/foo.cc:27:7: warning: iteration 100009 invokes undefined behavior [-Waggressive-loop-optimizations]
   f[i]=i;
   ~~~~^~
/in/foo.cc:25:15: note: within this loop
  for(int i=1;i<=N;i++)
              ~^~~