source_code: import java.util.*;
  import java.io.*;
  import java.math.*;
  public class Main
  {
      static class Reader 
      { 
          private InputStream mIs;private byte[] buf = new byte[1024];private int curChar,numChars;public Reader() { this(System.in); }public Reader(InputStream is) { mIs = is;} 
          public int read() {if (numChars == -1) throw new InputMismatchException();if (curChar >= numChars) {curChar = 0;try { numChars = mIs.read(buf);} catch (IOException e) { throw new InputMismatchException();}if (numChars <= 0) return -1; }return buf[curChar++];} 
          public String nextLine(){int c = read();while (isSpaceChar(c)) c = read();StringBuilder res = new StringBuilder();do {res.appendCodePoint(c);c = read();}while (!isEndOfLine(c));return res.toString() ;} 
          public String s(){int c = read();while (isSpaceChar(c)) c = read();StringBuilder res = new StringBuilder();do {res.appendCodePoint(c);c = read();}while (!isSpaceChar(c));return res.toString();} 
          public long l(){int c = read();while (isSpaceChar(c)) c = read();int sgn = 1;if (c == '-') { sgn = -1 ; c = read() ; }long res = 0; do{ if (c < '0' || c > '9') throw new InputMismatchException();res *= 10 ; res += c - '0' ; c = read();}while(!isSpaceChar(c));return res * sgn;} 
          public int i(){int c = read() ;while (isSpaceChar(c)) c = read();int sgn = 1;if (c == '-') { sgn = -1 ; c = read() ; }int res = 0;do{if (c < '0' || c > '9') throw new InputMismatchException();res *= 10 ; res += c - '0' ; c = read() ;}while(!isSpaceChar(c));return res * sgn;} 
          public double d() throws IOException {return Double.parseDouble(s()) ;}
          public boolean isSpaceChar(int c) { return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1; } 
          public boolean isEndOfLine(int c) { return c == '\n' || c == '\r' || c == -1; } 
          public int[] arr(int n){int[] ret = new int[n];for (int i = 0; i < n; i++) {ret[i] = i();}return ret;}
      }
      
      
   
             //       |----|       /\      |    |   -----   |
             //       |   /       /  \     |    |     |     |
             //       |--/       /----\    |----|     |     |
             //       |   \     /      \   |    |     |     |
             //       |    \   /        \  |    |   -----   -------
      
      public static long check(long mid,long x,long y,long n)
      {
          long ans=2*mid*mid+2*mid+1;
          long uleft=Math.max(0,mid-x+1);
          long dleft=Math.max(0,mid-(n-x));
          long lleft=Math.max(0,mid-y+1);
          long rleft=Math.max(0,mid-(n-y));
          ans-=uleft*uleft+dleft*dleft+lleft*lleft+rleft*rleft;
          
          ans+=(Math.max(0,mid-(x+y-1))*(Math.max(0,mid-(x+y-1))+1))/2;
          ans+=(Math.max(0,mid-(x+n-y))*(Math.max(0,mid-(x+n-y))+1))/2;
          ans+=(Math.max(0,mid-(y+n-x))*(Math.max(0,mid-(y+n-x))+1))/2;
          ans+=(Math.max(0,mid-(n-x+n-y+1))*(Math.max(0,mid-(n-x+n-y+1))+1))/2;
          return ans;
      }
      public static void main(String[] args)throws IOException
      {
          PrintWriter out= new PrintWriter(System.out);
          Reader sc=new Reader();
          long n=sc.l();
          long x=sc.l();
          long y=sc.l();
          long c=sc.l();
          long low=0;
          long high=(long)Math.pow(10,9);
          while(low<high)
          {
              long mid=(low+high)/2;
              if(check(mid,x,y,n)>=c)
              high=mid;
              else
              low=mid+1;
          }
          out.println(low);
          out.flush();
      }
  }