func_code_string: #include <bits/stdc++.h>   using namespace std;   const int M = 1e5, INF = 1e9;   const double PI = 3.141592653589793238462643383279502884197, eps = 1e-9;   int sum;   void getstring(int st, int ed, int n, bool val) {     string s;     sum = 0;     cout <<  ?  ;     for (int i = 0; i < st; i++) cout << 0;     for (int i = st; i < ed; i++)       cout << (i % 2 ? !val : val),           sum += ((val && i % 2 == 0) || (!val && i % 2));     for (int i = ed; i < n; i++) cout << 0;     cout << endl;   }   bool check(int cnt, int total, bool x) {     return (cnt != total + sum && x) || (cnt != total - sum && !x);   }   int main() {     int n, total, cnt, st, ed, md;     bool val, x;     string s1, s2;     cin >> n;     cout <<  ?  ;     for (int i = 0; i < n; i++) cout << 0;     cout << endl;     cin >> total;     cout <<  ?  ;     for (int i = 1; i < n; i++) cout << 0;     cout << 1 << endl;     cin >> cnt;     x = (cnt == total - 1);     getstring(0, n, n, 0);     cin >> cnt;     val = !check(cnt, total, !x);     st = 0, ed = n - 1;     while (st < ed) {       md = (st + ed) / 2;       getstring(st, md + 1, n, val);       cin >> cnt;       if (check(cnt, total, !x))         ed = md;       else         st = md + 1;     }     if (x)       cout <<  !   << st + 1 <<     << n;     else       cout <<  !   << n <<     << st + 1;     return 0;   }   