source_code: import java.io.*;
  import java.util.*;
  import java.math.*;
  
  public class P255D {
  
    @SuppressWarnings("unchecked")
    public void run() throws Exception {
      long n = nextLong();
      long x = nextLong();
      long y = nextLong();
      long c = nextLong();
  
      if ((n == 1) || (c == 1)) {
        println(0);
        return;
      }
  
      x = Math.min(x, n - x + 1);
      y = Math.min(y, n - y + 1);
      long t = 0;
      long s = 1;
  
      while (s < c) {
        t++;
  
        s += (t * 4) + ((t >= x + y) ? (t - x - y + 1) : 0)
             - ((t >= x) ? (t - x) * 2 + 1 : 0)
             - ((t >= y) ? (t - y) * 2 + 1 : 0)
             + ((t >= x + n - y + 1) ? (t - x - n + y) : 0)
             + ((t >= n - x + 1 + y) ? (t - n + x - y) : 0)
             - ((t >= n - x + 1) ? (t - n + x - 1) * 2 + 1 : 0)
             - ((t >= n - y + 1) ? (t - n + y - 1) * 2 + 1 : 0);
      }
  
      println(t);
    }
  
    public static void main(String... args) throws Exception {
      br = new BufferedReader(new InputStreamReader(System.in));
      pw = new PrintWriter(new BufferedOutputStream(System.out));
      new P255D().run();
      br.close();
      pw.close();
    }
  
    static BufferedReader br;
    static PrintWriter pw;
    StringTokenizer stok;
  
    String nextToken() throws IOException {
      while (stok == null || !stok.hasMoreTokens()) {
        String s = br.readLine();
        if (s == null) { return null; }
        stok = new StringTokenizer(s);
      }
      return stok.nextToken();
    }
  
    void print(byte b) { print("" + b); }
    void print(int i) { print("" + i); }
    void print(long l) { print("" + l); }
    void print(double d) { print("" + d); }
    void print(char c) { print("" + c); }
    void print(Object o) {
      if (o instanceof int[]) { print(Arrays.toString((int [])o));
      } else if (o instanceof long[]) { print(Arrays.toString((long [])o));
      } else if (o instanceof char[]) { print(Arrays.toString((char [])o));
      } else if (o instanceof byte[]) { print(Arrays.toString((byte [])o));
      } else if (o instanceof short[]) { print(Arrays.toString((short [])o));
      } else if (o instanceof boolean[]) { print(Arrays.toString((boolean [])o));
      } else if (o instanceof float[]) { print(Arrays.toString((float [])o));
      } else if (o instanceof double[]) { print(Arrays.toString((double [])o));
      } else if (o instanceof Object[]) { print(Arrays.toString((Object [])o));
      } else { print("" + o); }
    }
    void print(String s) { pw.print(s); }
    void println() { println(""); }
    void println(byte b) { println("" + b); }
    void println(int i) { println("" + i); }
    void println(long l) { println("" + l); }
    void println(double d) { println("" + d); }
    void println(char c) { println("" + c); }
    void println(Object o) { print(o); println(""); }
    void println(String s) { pw.println(s); }
    int nextInt() throws IOException { return Integer.parseInt(nextToken()); }
    long nextLong() throws IOException { return Long.parseLong(nextToken()); }
    double nextDouble() throws IOException { return Double.parseDouble(nextToken()); }
    char nextChar() throws IOException { return (char) (br.read()); }
    String next() throws IOException { return nextToken(); }
    String nextLine() throws IOException { return br.readLine(); }
    int [] readInt(int size) throws IOException {
      int [] array = new int [size];
      for (int i = 0; i < size; i++) { array[i] = nextInt(); }
      return array;
    }
    long [] readLong(int size) throws IOException {
      long [] array = new long [size];
      for (int i = 0; i < size; i++) { array[i] = nextLong(); }
      return array;
    }
    double [] readDouble(int size) throws IOException {
      double [] array = new double [size];
      for (int i = 0; i < size; i++) { array[i] = nextDouble(); }
      return array;
    }
    String [] readLines(int size) throws IOException {
      String [] array = new String [size];
      for (int i = 0; i < size; i++) { array[i] = nextLine(); }
      return array;
    }
  }