foo.cc: In function 'int main()':
foo.cc:36:43: warning: iteration 1000004 invokes undefined behavior [-Waggressive-loop-optimizations]
   36 |     for (int i = 1;i <= MAX;i++)father[i] = i;
      |                                 ~~~~~~~~~~^~~
foo.cc:36:22: note: within this loop
   36 |     for (int i = 1;i <= MAX;i++)father[i] = i;
      |                      ^

[Hydro](https://hydro.ac)提供评测服务