foo.cc: In function 'void solve()':
foo.cc:12:20: warning: iteration 50003 invokes undefined behavior [-Waggressive-loop-optimizations]
         if(!prime[i])
             ~~~~~~~^
foo.cc:10:22: note: within this loop
     for(int i = 2; i <= N; i++)
                    ~~^~~~
foo.cc:23:17: warning: iteration 50003 invokes undefined behavior [-Waggressive-loop-optimizations]
         prime[i]+=prime[i-1];
         ~~~~~~~~^~~~~~~~~~~~
foo.cc:22:22: note: within this loop
     for(int i = 2; i <= N; i++)
                    ~~^~~~