func_code_string: #include <bits/stdc++.h>   using namespace std;   const int fx[4][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};   const int fxx[8][2] = {{0, 1}, {0, -1}, {1, 0},  {-1, 0},                          {1, 1}, {1, -1}, {-1, 1}, {-1, -1}};   template <typename T, typename TT>   ostream& operator<<(ostream& s, pair<T, TT> t) {     return s <<  (  << t.first <<  ,  << t.second <<  ) ;   }   template <typename T>   ostream& operator<<(ostream& s, vector<T> t) {     for (int i = 0; i < ((int)(t.size())); i++)       s << t[i] << (i == ((int)(t.size())) - 1 ?   n  :    );     return s;   }   int start, finish, mid;   string answer;   int main() {     cin >> answer;     while (answer ==  start ) {       start = 0;       finish = 1;       while (true) {         cout <<  ?   << start <<     << finish << endl;         cin >> answer;         if (answer ==  x ) {           break;         }         start = finish;         finish <<= 1;       }       while (start < finish - 1) {         mid = (start + finish + 1) >> 1;         cout <<  ?   << start <<     << mid << endl;         cin >> answer;         if (answer[0] ==  x )           finish = mid;         else           start = mid;       }       cout <<  !   << finish << endl;       cin >> answer;     }     return 0;   }   