#include <bits/stdc++.h>
using namespace std;
const long long P = 1000000007LL;
long long N, x, y, c;
long long f(long long k) {
  long long ret = 2 * k * k + 2 * k + 1, a, b, d;
  d = ((x - N) < 0 ? -(x - N) : x - N);
  if (d < k) ret -= ((k - d) * (k - d));
  d = ((x - 1) < 0 ? -(x - 1) : x - 1);
  if (d < k) ret -= ((k - d) * (k - d));
  d = ((y - N) < 0 ? -(y - N) : y - N);
  if (d < k) ret -= ((k - d) * (k - d));
  d = ((y - 1) < 0 ? -(y - 1) : y - 1);
  if (d < k) ret -= ((k - d) * (k - d));
  a = ((x - (N + 1)) < 0 ? -(x - (N + 1)) : x - (N + 1)),
  b = ((y - (N + 1)) < 0 ? -(y - (N + 1)) : y - (N + 1));
  if (a + b <= k) ret += (k - a - b + 1) * (k - a - b + 2) / 2;
  a = ((x - (N + 1)) < 0 ? -(x - (N + 1)) : x - (N + 1)),
  b = ((y - 0) < 0 ? -(y - 0) : y - 0);
  if (a + b <= k) ret += (k - a - b + 1) * (k - a - b + 2) / 2;
  a = ((x - 0) < 0 ? -(x - 0) : x - 0),
  b = ((y - (N + 1)) < 0 ? -(y - (N + 1)) : y - (N + 1));
  if (a + b <= k) ret += (k - a - b + 1) * (k - a - b + 2) / 2;
  a = ((x - 0) < 0 ? -(x - 0) : x - 0), b = ((y - 0) < 0 ? -(y - 0) : y - 0);
  if (a + b <= k) ret += (k - a - b + 1) * (k - a - b + 2) / 2;
  return ret;
}
int main() {
  ios::sync_with_stdio(false);
  cin >> N >> x >> y >> c;
  long long lo = 0, hi = 2 * N, mit;
  for (; lo < hi;) {
    mit = (lo + hi) >> 1;
    if (c > f(mit))
      lo = mit + 1;
    else
      hi = mit;
  }
  cout << lo << endl;
  return 0;
}
