/in/foo.cc: In function 'int main()':
/in/foo.cc:17:6: warning: iteration 1009 invokes undefined behavior [-Waggressive-loop-optimizations]
  f[i]=i;
  ~~~~^~
/in/foo.cc:16:15: note: within this loop
  for(int i=1;i<=50000;i++)
              ~^~~~~~~