#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5, Mod = 1e9 + 7;
long long int pw1(long long int x) {
  if (x > 0) return x * x;
  return 0LL;
}
long long int pw2(long long int x) {
  if (x > 0) return x * (x + 1) / 2;
  return 0LL;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long int n, x, y, c;
  cin >> n >> x >> y >> c;
  long long int lo = 0, hi = 2 * n;
  --x, --y, --n;
  while (lo < hi) {
    long long int mid = (lo + hi) >> 1;
    long long int Now = 2 * mid * (mid + 1) + 1;
    Now -= pw1(mid - x);
    Now -= pw1(mid - y);
    Now -= pw1(mid + x - n);
    Now -= pw1(mid + y - n);
    Now += pw2(mid - x - y - 1);
    Now += pw2(mid - n + x - y - 1);
    Now += pw2(mid - n - x + y - 1);
    Now += pw2(mid - 2 * n + x + y - 1);
    if (Now >= c)
      hi = mid;
    else
      lo = mid + 1;
  }
  cout << lo << "\n";
  return 0;
}
