source_code: import java.io.OutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.io.PrintWriter;
  import java.io.BufferedWriter;
  import java.io.Writer;
  import java.io.OutputStreamWriter;
  import java.util.InputMismatchException;
  import java.io.IOException;
  import java.io.InputStream;
  
  /**
   * Built using CHelper plug-in
   * Actual solution is at the top
   *
   * @author Alex
   */
  public class Main {
      public static void main(String[] args) {
          InputStream inputStream = System.in;
          OutputStream outputStream = System.out;
          InputReader in = new InputReader(inputStream);
          OutputWriter out = new OutputWriter(outputStream);
          TaskB solver = new TaskB();
          solver.solve(1, in, out);
          out.close();
      }
  
      static class TaskB {
          int n;
          int startrow;
          int startcol;
          long want;
  
          boolean check(long time) {
              long max = (long) 2 * time * (time + 1) + 1;
              long highest = startrow - time;
              if(highest < 0) {
                  max -= Math.abs(highest) * Math.abs(highest);
              }
              long lowest = startrow + time;
              if(lowest >= n) {
                  max -= Math.abs(lowest - n + 1) * Math.abs(lowest - n + 1);
              }
              long leftmost = startcol - time;
              if(leftmost < 0) {
                  max -= Math.abs(leftmost) * Math.abs(leftmost);
              }
              long rightmost = startcol + time;
              if(rightmost >= n) {
                  max -= Math.abs(rightmost - n + 1) * Math.abs(rightmost - n + 1);
              }
              long upperright = time - (startrow + 1) - (n - startcol);
              if(upperright >= 0) {
                  max += (upperright + 1) * (upperright + 2) / 2;
              }
              long lowerright = time - (n - startrow) - (n - startcol);
              if(lowerright >= 0) {
                  max += (lowerright + 1) * (lowerright + 2) / 2;
              }
              long upperleft = time - (startrow + 1) - (startcol + 1);
              if(upperleft >= 0) {
                  max += (upperleft + 1) * (upperleft + 2) / 2;
              }
              long lowerleft = time - (n - startrow) - (startcol + 1);
              if(lowerleft >= 0) {
                  max += (lowerleft + 1) * (lowerleft + 2) / 2;
              }
              return max >= want;
          }
  
          public void solve(int testNumber, InputReader in, OutputWriter out) {
              n = in.readInt();
              startrow = in.readInt() - 1;
              startcol = in.readInt() - 1;
              want = in.readLong();
              long low = 0, high = 2 * n;
              while(low < high) {
                  long mid = (low + high) / 2;
                  if(check(mid)) high = mid;
                  else low = mid + 1;
              }
              out.printLine(low);
          }
  
      }
  
      static class InputReader {
          private InputStream stream;
          private byte[] buf = new byte[1024];
          private int curChar;
          private int numChars;
          private SpaceCharFilter filter;
  
          public InputReader(InputStream stream) {
              this.stream = stream;
          }
  
          public int read() {
              if(numChars == -1)
                  throw new InputMismatchException();
              if(curChar >= numChars) {
                  curChar = 0;
                  try {
                      numChars = stream.read(buf);
                  } catch(IOException e) {
                      throw new InputMismatchException();
                  }
                  if(numChars <= 0)
                      return -1;
              }
              return buf[curChar++];
          }
  
          public int readInt() {
              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 long readLong() {
              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 boolean isSpaceChar(int c) {
              if(filter != null)
                  return filter.isSpaceChar(c);
              return isWhitespace(c);
          }
  
          public static boolean isWhitespace(int c) {
              return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
          }
  
          public interface SpaceCharFilter {
              public boolean isSpaceChar(int ch);
  
          }
  
      }
  
      static class OutputWriter {
          private final PrintWriter writer;
  
          public OutputWriter(OutputStream outputStream) {
              writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
          }
  
          public OutputWriter(Writer writer) {
              this.writer = new PrintWriter(writer);
          }
  
          public void close() {
              writer.close();
          }
  
          public void printLine(long i) {
              writer.println(i);
          }
  
      }
  }
  
  