func_code_string: #include <bits/stdc++.h>   using namespace std;   long long x, y, n, c;   bool check(long long t) {     long long ans = 2 * t * t + 2 * t + 1;     if (x + t > n) {       long long m = x + t - n;       ans -= m * m;     }     if (y + t > n) {       long long m = y + t - n;       ans -= m * m;     }     if (x <= t) {       long long m = t - x + 1;       ans -= m * m;     }     if (y - t <= 0) {       long long m = t - y + 1;       ans -= m * m;     }     if (x - 1 + y - 1 < t) {       long long a = t - (x - 1 + y - 1) - 1;       ans += a * (a + 1) / 2;     }     if (x - 1 + n - y < t) {       long long a = t - (x - 1 + n - y) - 1;       ans += a * (a + 1) / 2;     }     if (n - x + y - 1 < t) {       long long a = t - (n - x + y - 1) - 1;       ans += a * (a + 1) / 2;     }     if (n - x + n - y < t) {       long long a = t - (n - x + n - y) - 1;       ans += a * (a + 1) / 2;     }     return ans >= c;   }   int main() {     while (cin >> n >> x >> y >> c) {       long long low = 0, high = 2 * n, mid, ans = 0;       while (low <= high) {         mid = (low + high) / 2;         if (check(mid)) {           ans = mid;           high = mid - 1;         } else           low = mid + 1;       }       cout << ans << endl;     }     return 0;   }   