func_code_string: #include <bits/stdc++.h>   using namespace std;   bool can(int x, int y, int a, int b) {     cout <<  ?   << x <<     << y <<     << a <<     << b << endl;     string ans;     cin >> ans;     if (ans ==  BAD ) exit(0);     return ans ==  YES ;   }   int main() {     ios::sync_with_stdio(false);     cin.tie(0);     int n;     cin >> n;     int x = 1, y = 1;     string ord1(n - 1,    ), ord2(n - 1,    );     int i = 0;     while (i < n - 1) {       if (can(x + 1, y, n, n)) {         ++x;         ord1[i] =  D ;       } else {         ord1[i] =  R ;         ++y;       }       ++i;     }     x = n;     y = n;     i = 0;     while (i < n - 1) {       if (can(1, 1, x, y - 1)) {         ord2[i] =  R ;         --y;       } else {         --x;         ord2[i] =  D ;       }       ++i;     }     reverse(ord2.begin(), ord2.end());     cout <<  !   << ord1 << ord2 << endl;   }   