func_code_string: #include <bits/stdc++.h>   using namespace std;   vector<int> v;   int main() {     v.push_back(0);     for (int i = 0; i < int(30); i++) v.push_back(1 << i);     while (1) {       int hi, lo;       int test;       string s;       cin >> s;       if (s ==  mistake  || s ==  end ) return 0;       bool found = 0;       for (int i = 0; i < int(30); i++) {         cout <<  ?   << v[i] <<     << v[i + 1] << endl;         fflush(stdout);         char c;         cin >> c;         if (c ==  e ) return 0;         if (c ==  x ) {           found = 1;           lo = v[i] + 1;           hi = v[i + 1];           test = v[i];           break;         }       }       if (!found) {         lo = v[v.size() - 1] + 1;         hi = 1000000000;         test = v[v.size() - 1];       }       while (hi - lo > 1) {         int mid = (lo + hi) / 2;         cout <<  ?   << test <<     << mid << endl;         fflush(stdout);         char c;         cin >> c;         if (c ==  e ) return 0;         if (c ==  x )           hi = mid;         else           lo = mid + 1;       }       cout <<  ?   << test <<     << lo << endl;       fflush(stdout);       char c;       cin >> c;       if (c ==  e ) return 0;       if (c ==  x )         cout <<  !   << lo << endl;       else         cout <<  !   << hi << endl;     }   }   