/in/foo.cc: In function 'int main()':
/in/foo.cc:12:16: warning: iteration 1000003 invokes undefined behavior [-Waggressive-loop-optimizations]
         if(!p[i])
             ~~~^
/in/foo.cc:10:18: note: within this loop
     for(int i=2;i<=MAXN;i++)
                  ^