Problem: Throughout Igor K.'s life he has had many situations worthy of attention. We remember the story with the virus, the story of his mathematical career and of course, his famous programming achievements. However, one does not always adopt new hobbies, one can quit something as well.

This time Igor K. got disappointed in one of his hobbies: editing and voicing videos. Moreover, he got disappointed in it so much, that he decided to destroy his secret archive for good. 

Igor K. use Pindows XR operation system which represents files and folders by small icons. At that, m icons can fit in a horizontal row in any window.

Igor K.'s computer contains n folders in the D: disk's root catalog. The folders are numbered from 1 to n in the order from the left to the right and from top to bottom (see the images). At that the folders with secret videos have numbers from a to b inclusive. Igor K. wants to delete them forever, at that making as few frame selections as possible, and then pressing Shift+Delete exactly once. What is the minimum number of times Igor K. will have to select the folder in order to select folders from a to b and only them? Let us note that if some selected folder is selected repeatedly, then it is deselected. Each selection possesses the shape of some rectangle with sides parallel to the screen's borders.

Input

The only line contains four integers n, m, a, b (1 ≤ n, m ≤ 109, 1 ≤ a ≤ b ≤ n). They are the number of folders in Igor K.'s computer, the width of a window and the numbers of the first and the last folders that need to be deleted.

Output

Print a single number: the least possible number of times Igor K. will have to select the folders using frames to select only the folders with numbers from a to b.

Examples

Input

11 4 3 9


Output

3


Input

20 5 2 20


Output

2

Note

The images below illustrate statement tests.

The first test:

<image>

In this test we can select folders 3 and 4 with out first selection, folders 5, 6, 7, 8 with our second selection and folder 9 with our third, last selection.

The second test:

<image>

In this test we can first select all folders in the first row (2, 3, 4, 5), then — all other ones.

Solution (in JAVA):

Solution:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.StringTokenizer;

/**
 * 
 * @author AmazingCaddy
 */
public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		// new Solve().solve_D();
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		MyInputReader in = new MyInputReader(inputStream);
		MyOutputWriter out = new MyOutputWriter(outputStream);
		new Solve().solve(in, out);
	}

}

class Solve {


	public void solve(MyInputReader in, MyOutputWriter out) {
		int n = in.nextInt();
		int m = in.nextInt();
		int a = in.nextInt();
		int b = in.nextInt();
		int ans=1;
		if(m == 1)
			ans=1;
		else if((a - 1) / m == (b - 1) / m)
			ans=1;
		else if(b == n){
			if(a % m == 1)
				ans=1;
			else
				ans=2;
		}else{
			if(a % m != 1)
				++ans;
			if(b % m != 0)
				++ans;
			if((a - 1) / m == (b - 1) / m - 1)
				ans = Math.min(ans,2);
			int na = (a - 1) % m;
			int nb = (b - 1) % m;
			if(na == nb + 1)
				ans = Math.min(ans,2);
		}

		out.printLine(ans);
		out.close();
	}
}

class MyInputReader {
	private BufferedReader reader;
	private StringTokenizer tokenizer;

	public MyInputReader(InputStream stream) {
		reader = new BufferedReader(new InputStreamReader(stream));
		tokenizer = null;
	}

	public String next() {
		while (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				String line = reader.readLine();
				if (line == null) {
					return null;
				}
				tokenizer = new StringTokenizer(line);
			} catch (IOException e) {
				return null;
				// throw new RuntimeException(e);
			}
		}
		return tokenizer.nextToken();
	}

	public Double nextDouble() {
		String strDouble = next();
		if (strDouble == null) {
			return null;
		}
		return Double.parseDouble(strDouble);
	}

	public Integer nextInt() {
		String strInt = next();
		if (strInt == null) {
			return null;
		}
		return Integer.parseInt(strInt);
	}

}

class MyOutputWriter {
	private final PrintWriter writer;

	public MyOutputWriter(OutputStream outputStream) {
		writer = new PrintWriter(outputStream);
	}

	public MyOutputWriter(Writer writer) {
		this.writer = new PrintWriter(writer);
	}

	public void print(Object... objects) {
		for (int i = 0; i < objects.length; i++) {
			if (i != 0)
				writer.print(' ');
			writer.print(objects[i]);
		}
	}

	public void printLine(Object... objects) {
		print(objects);
		writer.println();
	}

	public void close() {
		writer.close();
	}

}