/in/foo.cc: In function 'int main()':
/in/foo.cc:11:23: warning: iteration 20003 invokes undefined behavior [-Waggressive-loop-optimizations]
   11 |                 if(a[i]==0)
      |                    ~~~^
/in/foo.cc:9:22: note: within this loop
    9 |         for(int i=2;i<=N;i++)
      |                     ~^~~