/in/foo.cc: In function 'int main()':
/in/foo.cc:31:11: warning: iteration 2000014 invokes undefined behavior [-Waggressive-loop-optimizations]
      fa[i]=i;
      ~~~~~^~
/in/foo.cc:30:18: note: within this loop
     for(int i=0;i<=MOD+MOD;i++)
                 ~^~~~~~~~~