#include <bits/stdc++.h>
using namespace std;
const int maxn = 1000100;
const int INF = 1e9 + 10;
long long n, x, y, c;
long long g(long long k) {
  if (k <= 0) return 0;
  return k * k;
}
long long h(long long k) {
  if (k <= 0) return 0;
  return k * (k + 1) / 2;
}
long long f(long long k) {
  if (k < 0) return 0;
  return 1 + 2 * k * (k + 1) - g(y + k - n) - g(x + k - n) - g(1 - (y - k)) -
         g(1 - (x - k)) + h(y + k - n - x) + h(x + k - n - y) +
         h(y + k - n - (n - x + 1)) + h(1 - (y - k) - x);
}
long long bin(long long l, long long r, long long x) {
  long long res = r;
  while (l <= r) {
    long long m = (l + r) >> 1;
    long long F = f(m);
    if (F >= x)
      res = min(res, m), r = m - 1;
    else
      l = m + 1;
  }
  return res;
}
int main() {
  while (cin >> n >> x >> y >> c) {
    cout << bin(0, n * 3, c) << endl;
  }
  return 0;
}
