/in/foo.cc: In function 'int main()':
/in/foo.cc:21:18: warning: iteration 9999999 invokes undefined behavior [-Waggressive-loop-optimizations]
   ans[i]+=ans[i-1];
                  ^
/in/foo.cc:12:15: note: within this loop
  for(int i=2;i<=10000001;i++)
              ~^~~~~~~~~~