/in/foo.cc: In function 'int main()':
/in/foo.cc:12:9: warning: iteration 999997 invokes undefined behavior [-Waggressive-loop-optimizations]
   map[i]=s++;
   ~~~~~~^~~~
/in/foo.cc:11:15: note: within this loop
  for(int i=4;i<=1000001;i++){
              ~^~~~~~~~~