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 static java.lang.Math.*;
import java.util.*;
import java.io.*;

public class C {

    public void solve() throws Exception {
        
        long n = nextInt(), m = nextInt(), a = nextInt()-1, b = nextInt();
        long fullrows = b/m;
        if (b==n) b = (fullrows+1)*m;
//      debug(fullrows, b);
        
        //v jednom riadku alebo sa a,b rovnaju
        //jeden stlpec
        if (a/m == (b-1)/m || m==1) {
            println(1); return;
        }
        
        //obdlznik
        if (a%m==0 && b%m==0) {
            println(1); return;
        }
        
        //za sebou iduce riadky
        if (a/m + 1 == (b-1)/m) {
            println(2); return;
        }
        
        //zac. alebo konci na kraji
        if (a%m==0 || b%m==0) {
            println(2); return;
        }
        
        //dva obdlzniky
        if ((b-a)%m==0) {
            println(2); return;
        }
        
        println(3);
        
    }

    

    ////////////////////////////////////////////////////////////////////////////

    boolean showDebug = true;

    double EPS = 1e-7;
    int INF = Integer.MAX_VALUE;
    long INFL = Long.MAX_VALUE;
    double INFD = Double.MAX_VALUE;

    
    int absPos(int i) {
        return i<0 ? 0:i;
    }
    long absPos(long i) {
        return i<0 ? 0:i;
    }
    double absPos(double i) {
        return i<0 ? 0:i;
    }
    
    int min(int... nums) {
        int r = INF;
        for (int i: nums)
            if (i<r) r=i;
        return r;
    }
    int max(int... nums) {
        int r = -INF;
        for (int i: nums)
            if (i>r) r=i;
        return r;
    }
    long minL(long... nums) {
        long r = INFL;
        for (long i: nums)
            if (i<r) r=i;
        return r;
    }
    long maxL(long... nums) {
        long r = -INFL;
        for (long i: nums)
            if (i>r) r=i;
        return r;
    }
    double minD(double... nums) {
        double r = INFD;
        for (double i: nums)
            if (i<r) r=i;
        return r;
    }
    double maxD(double... nums) {
        double r = -INFD;
        for (double i: nums)
            if (i>r) r=i;
        return r;
    }
    long sumArr(int[] arr) {
        long res = 0;
        for (int i: arr)
            res+=i;
        return res;
    }
    long sumArr(long[] arr) {
        long res = 0;
        for (long i: arr)
            res+=i;
        return res;
    }
    double sumArr(double[] arr) {
        double res = 0;
        for (double i: arr)
            res+=i;
        return res;
    }

    long partsFitCnt(long partSize, long wholeSize) {
        return (partSize+wholeSize-1)/partSize;
    }

    boolean odd(long i) {
        return (i&1)==1;
    }

    long binpow(int x, int n) {
        long r = 1;
        while (n>0) {
            if ((n&1)!=0) r*=x;
            x*=x;
            n>>=1;
        }
        return r;
    }


    String str(Object o) {
        return o.toString();
    }


    long timer = System.currentTimeMillis();
    void startTimer() {
        timer = System.currentTimeMillis();
    }
    void stopTimer() {
        System.err.println("time: "+(System.currentTimeMillis()-timer)/1000.0);
    }


    class InputReader {
        byte[] buf = new byte[1<<16];
        int bufPos = 0, bufLim = -1;
        char read() throws IOException {
            if (bufPos>=bufLim) {
                bufLim = System.in.read(buf);
                bufPos = 0;
            }
            return (char)buf[bufPos++];
        }
    }

    InputReader in = new InputReader();
    static BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out), 1<<16);

    char nextInput() throws IOException {
        return in.read();
    }
    char nextChar() throws IOException {
        char c = in.read();
        while (c<=' ') c=in.read();
        return c;
    }
    String nextWord() throws IOException {
        StringBuilder sb = new StringBuilder();
        char c = in.read();
        while (c<=' ') c=in.read();
        while (c>' ') {
            sb.append(c);
            c = in.read();
        }
        return new String(sb);
    }
    String nextLine() throws IOException {
        StringBuilder sb = new StringBuilder();
        char c = in.read();
        while (c<=' ') c=in.read();
        while (c!='\n' && c!='\r') {
            sb.append(c);
            c = in.read();
        }
        return new String(sb);
    }
    int nextInt() throws IOException {
        int r = 0;
        char c = nextChar();
        boolean neg = false;
        if (c=='-') neg=true;
        else r = c-48;
        c = nextInput();
        while (c>='0' && c<='9') {
            r*=10;
            r+=c-48;
            c=nextInput();
        }
        return neg ? -r:r;
    }
    long nextLong() throws IOException {
        long r = 0;
        char c = nextChar();
        boolean neg = false;
        if (c=='-') neg=true;
        else r = c-48;
        c = nextInput();
        while (c>='0' && c<='9') {
            r*=10L;
            r+=c-48L;
            c=nextInput();
        }
        return neg ? -r:r;
    }
    double nextDouble() throws NumberFormatException, IOException {
        return Double.parseDouble(nextWord());
    }
    int[] nextArr(int size) throws NumberFormatException, IOException {
        int[] arr = new int[size];
        for (int i=0; i<size; i++)
            arr[i] = nextInt();
        return arr;
    }
    long[] nextArrL(int size) throws NumberFormatException, IOException {
        long[] arr = new long[size];
        for (int i=0; i<size; i++)
            arr[i] = nextLong();
        return arr;
    }
    double[] nextArrD(int size) throws NumberFormatException, IOException {
        double[] arr = new double[size];
        for (int i=0; i<size; i++)
            arr[i] = nextDouble();
        return arr;
    }
    String[] nextArrS(int size) throws NumberFormatException, IOException {
        String[] arr = new String[size];
        for (int i=0; i<size; i++)
            arr[i] = nextWord();
        return arr;
    }
    char[] nextArrCh(int size) throws IOException {
        char[] arr = new char[size];
        for (int i=0; i<size; i++)
            arr[i] = nextChar();
        return arr;
    }
    char[][] nextArrCh(int rows, int columns) throws IOException {
        char[][] arr = new char[rows][columns];
        for (int i=0; i<rows; i++)
            for (int j=0; j<columns; j++)
                arr[i][j] = nextChar();
        return arr;
    }

    void print(Object o) throws IOException {
        out.write(o.toString());
    }
    void println(Object o) throws IOException {
        out.write(o.toString());
        out.newLine();
    }
    void print(Object... o) throws IOException {
        for (int i=0; i<o.length; i++) {
            if (i!=0) out.write(' ');
            out.write(o[i].toString());
        }
    }
    void println(Object... o) throws IOException {
        print(o);
        out.newLine();
    }
    void printn(Object o, int n) throws IOException {
        String s = o.toString();
        for (int i=0; i<n; i++) {
            out.write(s);
            if (i!=n-1) out.write(' ');
        }
    }
    void printnln(Object o, int n) throws IOException {
        printn(o, n);
        out.newLine();
    }
    void printArr(int[] arr) throws IOException {
        for (int i=0; i<arr.length; i++) {
            if (i!=0) out.write(' ');
            out.write(Integer.toString(arr[i]));
        }
    }
    void printArr(long[] arr) throws IOException {
        for (int i=0; i<arr.length; i++) {
            if (i!=0) out.write(' ');
            out.write(Long.toString(arr[i]));
        }
    }
    void printArr(double[] arr) throws IOException {
        for (int i=0; i<arr.length; i++) {
            if (i!=0) out.write(' ');
            out.write(Double.toString(arr[i]));
        }
    }
    void printArr(String[] arr) throws IOException {
        for (int i=0; i<arr.length; i++) {
            if (i!=0) out.write(' ');
            out.write(arr[i]);
        }
    }
    void printArr(char[] arr) throws IOException {
        for (char c: arr) out.write(c);
    }
    void printlnArr(int[] arr) throws IOException {
        printArr(arr);
        out.newLine();
    }
    void printlnArr(long[] arr) throws IOException {
        printArr(arr);
        out.newLine();
    }
    void printlnArr(double[] arr) throws IOException {
        printArr(arr);
        out.newLine();
    }
    void printlnArr(String[] arr) throws IOException {
        printArr(arr);
        out.newLine();
    }
    void printlnArr(char[] arr) throws IOException {
        printArr(arr);
        out.newLine();
    }

    void debug(Object... o) {
        if (showDebug) System.err.println(Arrays.deepToString(o));
    }


    public static void main(String[] args) throws Exception {
        Locale.setDefault(Locale.US);
        new C().solve();
        out.flush(); out.close();
    }
}