func_code_string: #include <bits/stdc++.h>   using namespace std;   long long l, r, n, k;   string Bad;   int ask(long long l, long long r) {     cout << l <<     << r << endl;     cout.flush();     cin >> Bad;     if (Bad[0] ==  B ) exit(0);     if (Bad[0] ==  Y ) {       if (l == r) exit(0);       return 1;     }     return 0;   }   int main() {     srand(2109888);     cin >> n >> k;     l = 1;     r = n;     while (l <= r) {       long long mid = (l + r) >> 1;       if (ask(l, mid))         r = mid;       else         l = mid + 1;       l = max(1ll, l - k);       r = min(n, r + k);       mid = l + rand() % (r - l + 1);       ask(mid, mid);       l = max(1ll, l - k);       r = min(n, r + k);     }     return 0;   }   