answer.code: In function ‘int main()’:
answer.code:96:3: error: ‘cin’ was not declared in this scope
   96 |   cin.tie(0)->sync_with_stdio(false);
      |   ^~~
answer.code:3:1: note: ‘std::cin’ is defined in header ‘<iostream>’; did you forget to ‘#include <iostream>’?
    2 | #include <cstring>
  +++ |+#include <iostream>
    3 | 
answer.code:119:7: error: ‘cout’ was not declared in this scope
  119 |       cout << f[rt] << '\n';
      |       ^~~~
answer.code:119:7: note: ‘std::cout’ is defined in header ‘<iostream>’; did you forget to ‘#include <iostream>’?