/in/foo.cc: In function 'int main()':
/in/foo.cc:25:31: warning: iteration 109 invokes undefined behavior [-Waggressive-loop-optimizations]
   25 |         rep(i , 1 , M) two[i] = two[i - 1] * 2;
      |                        ~~~~~~~^~~~~~~~~~~~~~~~
/in/foo.cc:3:42: note: within this loop
    3 | #define rep(i , a , b) for(int i = a ; i <= b ; i ++)
      |                                          ^
/in/foo.cc:25:9: note: in expansion of macro 'rep'
   25 |         rep(i , 1 , M) two[i] = two[i - 1] * 2;
      |         ^~~