/in/foo.cc: In function 'int main()':
/in/foo.cc:32:45: warning: iteration 300007 invokes undefined behavior [-Waggressive-loop-optimizations]
         pre_sumX[i]=pre_sumX[i-1]+bucket_X[i];
                                   ~~~~~~~~~~^
/in/foo.cc:30:19: note: within this loop
     for(int i=1; i<=MAX_M; ++i)
                  ~^~~~~~~