#include <bits/stdc++.h>
using namespace std;
int n, c, x, y;
long long g(long long a) {
  if (a <= 0) return 0;
  return a * a;
}
long long f(long long a) {
  if (a <= 0) return 0;
  return (a * (a + 1)) / 2;
}
long long T(long long t) { return 2 * t * t + 2 * t + 1; }
long long calc(int t) {
  int a1, a2, b1, b2;
  b1 = max(1, x - t);
  b2 = min(x + t, n);
  a1 = max(1, y - t);
  a2 = min(n, y + t);
  long long cnt = T(t);
  cnt -= g(y + t - a2);
  cnt -= g(a1 - y + t);
  cnt -= g(x + t - b2);
  cnt -= g(b1 - x + t);
  cnt += f(t - (x - b1) - (a2 - y) - 1);
  cnt += f(t - (x - b1) - (y - a1) - 1);
  cnt += f(t - (b2 - x) - (a2 - y) - 1);
  cnt += f(t - (b2 - x) - (y - a1) - 1);
  return cnt;
}
int main(int nargs, char* args[]) {
  cin >> n >> x >> y >> c;
  if (c == 1) {
    puts("0");
    return 0;
  }
  int lo = 0, hi = 2 * n, mid;
  while (hi - lo > 1) {
    mid = (lo + hi) / 2;
    if (calc(mid) < c)
      lo = mid;
    else
      hi = mid;
  }
  cout << hi << endl;
}
