#include <bits/stdc++.h>
#pragma GCC optimize(1)
#pragma G++ optimize(1)
#pragma GCC optimize(2)
#pragma G++ optimize(2)
#pragma GCC optimize(3)
#pragma G++ optimize(3)
#pragma GCC optimize(4)
#pragma G++ optimize(4)
#pragma GCC optimize(5)
#pragma G++ optimize(5)
#pragma GCC optimize(6)
#pragma G++ optimize(6)
#pragma GCC optimize(7)
#pragma G++ optimize(7)
#pragma GCC optimize(8)
#pragma G++ optimize(8)
#pragma GCC optimize(9)
#pragma G++ optimize(9)
#pragma GCC optimize("-funsafe-loop-optimizations")
#pragma GCC optimize("-funroll-loops")
#pragma GCC optimize("-fwhole-program")
#pragma GCC optimize("Ofast,no-stack-protector")
#pragma GCC optimize("-fthread-jumps")
#pragma GCC optimize("-falign-functions")
#pragma GCC optimize("-falign-jumps")
#pragma GCC optimize("-falign-loops")
#pragma GCC optimize("-falign-labels")
#pragma GCC optimize("-fcaller-saves")
#pragma GCC optimize("-fcrossjumping")
#pragma GCC optimize("-fcse-follow-jumps")
#pragma GCC optimize("-fcse-skip-blocks")
#pragma GCC optimize("-fdelete-null-pointer-checks")
#pragma GCC optimize("-fdevirtualize")
#pragma GCC optimize("-fexpensive-optimizations")
#pragma GCC optimize("-fgcse")
#pragma GCC optimize("-fgcse-lm")
#pragma GCC optimize("-fhoist-adjacent-loads")
#pragma GCC optimize("-finline-small-functions")
#pragma GCC optimize("-findirect-inlining")
#pragma GCC optimize("-fipa-sra")
#pragma GCC optimize("-foptimize-sibling-calls")
#pragma GCC optimize("-fpartial-inlining")
#pragma GCC optimize("-fpeephole2")
#pragma GCC optimize("-freorder-blocks")
#pragma GCC optimize("-freorder-functions")
#pragma GCC optimize("-frerun-cse-after-loop")
#pragma GCC optimize("-fsched-interblock")
#pragma GCC optimize("-fsched-spec")
#pragma GCC optimize("-fschedule-insns")
#pragma GCC optimize("-fschedule-insns2")
#pragma GCC optimize("-fstrict-aliasing")
#pragma GCC optimize("-fstrict-overflow")
#pragma GCC optimize("-ftree-switch-conversion")
#pragma GCC optimize("-ftree-tail-merge")
#pragma GCC optimize("-ftree-pre")
#pragma GCC optimize("-ftree-vrp")
using namespace std;
const int INF = 2147483647;
const double PI = 3.1415926535897932384626;
const int maxn = 10005;
struct bign {
  int d[maxn], len;
  inline void clean() {
    while (len > 1 && !d[len - 1]) len--;
  }
  inline bign() {
    memset(d, 0, sizeof(d));
    len = 1;
  }
  inline bign(int num) { *this = num; }
  inline bign(char* num) { *this = num; }
  inline bign operator=(const char* num) {
    memset(d, 0, sizeof(d));
    len = strlen(num);
    for (int i = 0; i < len; i++) d[i] = num[len - 1 - i] - '0';
    clean();
    return *this;
  }
  inline bign operator=(int num) {
    char s[20];
    sprintf(s, "%d", num);
    *this = s;
    return *this;
  }
  inline bign operator+(const bign& b) {
    bign c = *this;
    int i;
    for (i = 0; i < b.len; i++) {
      c.d[i] += b.d[i];
      if (c.d[i] > 9) c.d[i] %= 10, c.d[i + 1]++;
    }
    while (c.d[i] > 9) c.d[i++] %= 10, c.d[i]++;
    c.len = max(len, b.len);
    if (c.d[i] && c.len <= i) c.len = i + 1;
    return c;
  }
  inline bign operator-(const bign& b) {
    bign c = *this;
    int i;
    for (i = 0; i < b.len; i++) {
      c.d[i] -= b.d[i];
      if (c.d[i] < 0) c.d[i] += 10, c.d[i + 1]--;
    }
    while (c.d[i] < 0) c.d[i++] += 10, c.d[i]--;
    for (i = c.len - 1; i > 0; i--)
      if (c.d[i] != 0) break;
    c.len = i + 1;
    return c;
  }
  inline bign operator*(const bign& b) const {
    int i, j;
    bign c;
    c.len = len + b.len;
    for (j = 0; j < b.len; j++)
      for (i = 0; i < len; i++) c.d[i + j] += d[i] * b.d[j];
    for (i = 0; i < c.len - 1; i++) c.d[i + 1] += c.d[i] / 10, c.d[i] %= 10;
    c.clean();
    return c;
  }
  inline bign operator/(const bign& b) {
    int i, j;
    bign c = *this, a = 0;
    for (i = len - 1; i >= 0; i--) {
      a = a * 10 + d[i];
      for (j = 0; j < 10; j++)
        if (a < b * (j + 1)) break;
      c.d[i] = j;
      a = a - b * j;
    }
    c.clean();
    return c;
  }
  inline bign operator%(const bign& b) {
    int i, j;
    bign a = 0;
    for (i = len - 1; i >= 0; i--) {
      a = a * 10 + d[i];
      for (j = 0; j < 10; j++)
        if (a < b * (j + 1)) break;
      a = a - b * j;
    }
    return a;
  }
  inline bign operator+=(const bign& b) {
    *this = *this + b;
    return *this;
  }
  inline bign operator*=(const bign& b) {
    *this = *this * b;
    return *this;
  }
  inline bign operator-=(const bign& b) {
    *this = *this - b;
    return *this;
  }
  inline bign operator/=(const bign& b) {
    *this = *this / b;
    return *this;
  }
  inline bool operator<(const bign& b) const {
    if (len != b.len) return len < b.len;
    for (int i = len - 1; i >= 0; i--)
      if (d[i] != b.d[i]) return d[i] < b.d[i];
    return false;
  }
  inline bool operator>(const bign& b) const { return b < *this; }
  inline bool operator<=(const bign& b) const { return !(b < *this); }
  inline bool operator>=(const bign& b) const { return !(*this < b); }
  inline bool operator!=(const bign& b) const { return b < *this || *this < b; }
  inline bool operator==(const bign& b) const {
    return !(b < *this) && !(b > *this);
  }
  inline string str() const {
    char s[maxn] = {};
    for (int i = 0; i < len; i++) s[len - 1 - i] = d[i] + '0';
    return s;
  }
};
inline istream& operator>>(istream& in, bign& x) {
  string s;
  in >> s;
  x = s.c_str();
  return in;
}
inline ostream& operator<<(ostream& out, const bign& x) {
  out << x.str();
  return out;
}
inline void write(long long x) {
  if (x < 0) putchar('-'), x = -x;
  if (x > 9) write(x / 10);
  putchar(x % 10 + '0');
}
inline int pt(int a[], int l, int r) {
  int p, i, j;
  p = a[l];
  i = l;
  j = r + 1;
  for (;;) {
    while (a[++i] < p)
      if (i >= r) break;
    while (a[--j] > p)
      if (j <= l) break;
    if (i >= j)
      break;
    else
      swap(a[i], a[j]);
  }
  if (j == l) return j;
  swap(a[l], a[j]);
  return j;
}
inline void q_sort(int a[], int l, int r) {
  int q;
  if (r > l) {
    q = pt(a, l, r);
    q_sort(a, l, q - 1);
    q_sort(a, q + 1, r);
  }
}
inline void write(int x) {
  if (x < 0) putchar('-'), x = -x;
  if (x > 9) write(x / 10);
  putchar(x % 10 + '0');
}
inline void rd(long long& val) {
  long long x = 0;
  int f = 1;
  char ch = getchar();
  while ((ch < '0' || ch > '9') && ch != '-') ch = getchar();
  if (ch == '-') {
    f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  val = x * f;
}
inline void rd(int& val) {
  int x = 0;
  int f = 1;
  char ch = getchar();
  while ((ch < '0' || ch > '9') && ch != '-') ch = getchar();
  if (ch == '-') {
    f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  val = x * f;
}
inline void _write(int x) {
  write(x);
  putchar(' ');
}
inline void print(int x) {
  write(x);
  putchar('\n');
}
inline void _write(long long x) {
  write(x);
  putchar(' ');
}
inline void print(long long x) {
  write(x);
  putchar('\n');
}
struct PII {
  int first, second;
  PII() {}
  PII(int f, int s) : first(f), second(s) {}
  inline bool operator<(const PII& x) const {
    if (first != x.first) return first < x.first;
    return second < x.second;
  }
  inline bool operator==(const PII& x) const {
    return first == x.first and second == x.second;
  }
  inline bool operator>(const PII& x) const {
    if (first != x.first) return first > x.first;
    return second > x.second;
  }
  inline bool operator!=(const PII& x) const {
    return first != x.first and second != x.second;
  }
};
ofstream out;
ifstream in;
inline string itos(int x) {
  string rt = "";
  while (x) rt = (char)(x % 10 + '0') + rt, x /= 10;
  return rt;
}
clock_t __stt;
inline void TStart() { __stt = clock(); }
inline void TReport() {
  printf("\nTaken Time : %.3lf sec\n",
         (double)(clock() - __stt) / CLOCKS_PER_SEC);
}
long long n, x, y, c;
inline long long sd(long long t) { return pow(max(0ll, t), 2); }
inline long long cnr(long long t) {
  --t;
  if (t < 0) return 0ll;
  return t * (t + 1) / 2;
}
inline long long solve(long long t) {
  long long a = 2 * (t + 1) * (t + 1) - (2 * t + 1);
  a -= sd(t - (x - 1)) + sd(t - (n - x)) + sd(t - (y - 1)) + sd(t - (n - y));
  a += cnr(t - (x - 1 + y - 1)) + cnr(t - (n - x + y - 1)) +
       cnr(t - (n - x + n - y)) + cnr(t - (n - y + x - 1));
  return a;
}
int main() {
  ios_base::sync_with_stdio(false);
  int i, j;
  cin >> n >> x >> y >> c;
  long long l = 0, r = n + 100, md;
  while (l < r) {
    md = (l + r) / 2;
    if (solve(md) < c)
      l = md + 1;
    else
      r = md;
  }
  cout << l << endl;
}
