#include <bits/stdc++.h>
using namespace std;
const int inf = (int)1e9;
int main() {
  int n, x, y, c;
  scanf("%d%d%d%d", &n, &x, &y, &c);
  int lb = 0, ub = n * 2 + 10;
  if (c == 1) ub = 0;
  while (ub - lb > 1) {
    long long mid = (lb + ub) / 2;
    long long sum = 0;
    long long up = max<long long>(mid + 1 - x, 0);
    long long left = max<long long>(mid + 1 - y, 0);
    long long down = max<long long>(mid + x - n, 0);
    long long right = max<long long>(mid + y - n, 0);
    long long cut1 = max<long long>(up - y, 0);
    long long cut2 = max<long long>(up + y - 1 - n, 0);
    long long cut3 = max<long long>(down - y, 0);
    long long cut4 = max<long long>(down + y - 1 - n, 0);
    sum += 2 * mid * mid + 2 * mid + 1;
    sum -= up * up;
    sum -= down * down;
    sum -= left * left;
    sum -= right * right;
    sum += cut1 * (cut1 + 1) / 2;
    sum += cut2 * (cut2 + 1) / 2;
    sum += cut3 * (cut3 + 1) / 2;
    sum += cut4 * (cut4 + 1) / 2;
    if (sum < c)
      lb = mid;
    else
      ub = mid;
  }
  int ans = ub;
  printf("%d\n", ans);
  return 0;
}
