answer.code: In function ‘int main()’:
answer.code:18:7: error: ‘memset’ was not declared in this scope
   18 |       memset(f,0,sizeof(f));
      |       ^~~~~~
answer.code:2:1: note: ‘memset’ is defined in header ‘<cstring>’; did you forget to ‘#include <cstring>’?
    1 | #include<iostream>
  +++ |+#include <cstring>
    2 | #define M 10005