answer.code: In function ‘int main()’:
answer.code:49:21: error: ‘read’ was not declared in this scope; did you mean ‘fread’?
   49 |                 opt=read();
      |                     ^~~~
      |                     fread
answer.code:51:30: error: ‘l’ was not declared in this scope
   51 |                         cin>>l>>r;
      |                              ^
answer.code:51:33: error: ‘r’ was not declared in this scope
   51 |                         cin>>l>>r;
      |                                 ^
answer.code:55:30: error: ‘x’ was not declared in this scope
   55 |                         cin>>x;
      |                              ^
answer.code: In function ‘char query(int, int, int, ll)’:
answer.code:43:1: warning: control reaches end of non-void function [-Wreturn-type]
   43 | }
      | ^