#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, x, y, c;
  cin >> n >> x >> y >> c;
  long long ans = 1, v1 = -1, v2 = -1, g1 = -1, g2 = -1, vg1 = -1, vg2 = -1,
            vg3 = -1, vg4 = -1, r = 0;
  int tv1 = 0, tv2 = 0, tg1 = 0, tg2 = 0;
  int i = 0;
  int tmp;
  for (; ans < c; i++) {
    ans += r;
    r += 4;
    if (v1 != -1) v1 += 2;
    if (v2 != -1) v2 += 2;
    if (g1 != -1) g1 += 2;
    if (g2 != -1) g2 += 2;
    if (vg1 != -1) vg1++;
    if (vg2 != -1) vg2++;
    if (vg3 != -1) vg3++;
    if (vg4 != -1) vg4++;
    if (v1 == -1 && (y + i) > n) {
      v1 = 1;
      tv1 = i;
    }
    if (g1 == -1 && (x + i) > n) {
      g1 = 1;
      tg1 = i;
    }
    if (g2 == -1 && (x - i) < 1) {
      g2 = 1;
      tg2 = i;
    }
    if (v2 == -1 && (y - i) < 1) {
      v2 = 1;
      tv2 = i;
    }
    if (vg1 == -1 && tv1 != 0 && tg1 != 0 && (tv1 + tg1) <= i) vg1 = 1;
    if (vg2 == -1 && tv1 != 0 && tg2 != 0 && (tv1 + tg2) <= i) vg2 = 1;
    if (vg3 == -1 && tv2 != 0 && tg1 != 0 && (tv2 + tg1) <= i) vg3 = 1;
    if (vg4 == -1 && tv2 != 0 && tg2 != 0 && (tv2 + tg2) <= i) vg4 = 1;
    if (v1 != -1) ans -= v1;
    if (v2 != -1) ans -= v2;
    if (g1 != -1) ans -= g1;
    if (g2 != -1) ans -= g2;
    if (vg1 != -1) ans += vg1;
    if (vg2 != -1) ans += vg2;
    if (vg3 != -1) ans += vg3;
    if (vg4 != -1) ans += vg4;
    if (ans >= c) break;
  }
  cout << i;
  return 0;
}
