answer.code: In function ‘bool Read(int)’:
answer.code:16:22: error: ‘flag’ was not declared in this scope; did you mean ‘_flag’?
   16 |   if (cas==1&&n==_n) flag=1;
      |                      ^~~~
      |                      _flag
answer.code: In function ‘int main()’:
answer.code:216:15: error: return-statement with no value, in function returning ‘int’ [-fpermissive]
  216 |   if (!_flag) return;
      |               ^~~~~~