Manao has a monitor. The screen of the monitor has horizontal to vertical length ratio a:b. Now he is going to watch a movie. The movie's frame has horizontal to vertical length ratio c:d. Manao adjusts the view in such a way that the movie preserves the original frame ratio, but also occupies as much space on the screen as possible and fits within it completely. Thus, he may have to zoom the movie in or out, but Manao will always change the frame proportionally in both dimensions.

Calculate the ratio of empty screen (the part of the screen not occupied by the movie) to the total screen size. Print the answer as an irreducible fraction p / q.

Input

A single line contains four space-separated integers a, b, c, d (1 ≤ a, b, c, d ≤ 1000).

Output

Print the answer to the problem as "p/q", where p is a non-negative integer, q is a positive integer and numbers p and q don't have a common divisor larger than 1.

Examples

Input

1 1 3 2


Output

1/3


Input

4 3 2 2


Output

1/4

Note

Sample 1. Manao's monitor has a square screen. The movie has 3:2 horizontal to vertical length ratio. Obviously, the movie occupies most of the screen if the width of the picture coincides with the width of the screen. In this case, only 2/3 of the monitor will project the movie in the horizontal dimension: <image>

Sample 2. This time the monitor's width is 4/3 times larger than its height and the movie's frame is square. In this case, the picture must take up the whole monitor in the vertical dimension and only 3/4 in the horizontal dimension: <image>
import java.util.*;
import java.lang.*;
import java.io.*;
import java.math.*;

public class Codeforces {

    static double Phi = (1 + Math.sqrt(5)) / 2.0;
    static int MAX = -1 >>> 1;
    static long MODL = 1_000_000_007L;
    static int MOD = 1_000_000_007;
    static void no() throws IOException {println("NO");}
    static void yes() throws IOException {println("YES");}

    static boolean testCases = false;
    static boolean DEBUG = true;

    static void main() throws Exception {
        long a = nl();
        long b = nl();
        long c = nl();
        long d = nl();

        long λ1, λ2;
        if(b * c <= a * d) {
            λ1 = b;
            λ2 = d;
        } else {
            λ1 = a;
            λ2 = c;
        }

        debug(λ1 + " " + λ2);

        long num = λ2 * λ2 * a * b - c * d * λ1 * λ1;
        long den = a * b * λ2 * λ2;

        debug(num + " " + den);

        long gcd = gcd(num, den);

        debug("gcd = " + gcd);

        num /= gcd;
        den /= gcd;
        println(num + "/" + den);
    }

    static long gcd(long a, long b) {
        if (b == 0)
            return a;
        return gcd(b, a % b);
    }

    public static void main(String[] args) throws Exception {
        long startPointTime = System.currentTimeMillis();
        scannerIn = System.in;
        printerBW = new BufferedWriter(new OutputStreamWriter(System.out));
        if (DEBUG && System.getProperty("ONLINE_JUDGE") == null) {
            HABLA = true;
            debug("Debugging enabled");
        }

        int t = testCases ? ni() : 1;
        int to = t;
        while (t-- > 0) {
            debug("Case #" + (to - t) + " ---------------- ");
            main();
        }
        long endTime = System.currentTimeMillis();
        float totalProgramTime = endTime - startPointTime;
        if (HABLA)
            debug("Execution time is " + totalProgramTime + " (" + (totalProgramTime / 1000) + "s)");
        close();
    }

    //IO Stuff
    private static boolean HABLA = false;
    private static byte[] scannerByteBuffer = new byte[1024]; // Buffer of Bytes
    private static int scannerIndex;
    private static InputStream scannerIn;
    private static int scannerTotal;
    private static BufferedWriter printerBW;

    private static int next() throws IOException { // Scan method used to scan buf
        if (scannerTotal < 0)
            throw new InputMismatchException();
        if (scannerIndex >= scannerTotal) {
            scannerIndex = 0;
            scannerTotal = scannerIn.read(scannerByteBuffer);
            if (scannerTotal <= 0)
                return -1;
        }
        return scannerByteBuffer[scannerIndex++];
    }

    static int ni() throws IOException {
        int integer = 0;
        int n = next();
        while (isWhiteSpace(n)) // Removing startPointing whitespaces
            n = next();
        int neg = 1;
        if (n == '-') { // If Negative Sign encounters
            neg = -1;
            n = next();
        }
        while (!isWhiteSpace(n)) {
            if (n >= '0' && n <= '9') {
                integer *= 10;
                integer += n - '0';
                n = next();
            } else
                throw new InputMismatchException();
        }
        return neg * integer;
    }

    static long nl() throws IOException {
        long integer = 0;
        int n = next();
        while (isWhiteSpace(n)) // Removing startPointing whitespaces
            n = next();
        int neg = 1;
        if (n == '-') { // If Negative Sign encounters
            neg = -1;
            n = next();
        }
        while (!isWhiteSpace(n)) {
            if (n >= '0' && n <= '9') {
                integer *= 10;
                integer += n - '0';
                n = next();
            } else
                throw new InputMismatchException();
        }
        return neg * integer;
    }

    static String line() throws IOException {
        StringBuilder sb = new StringBuilder();
        int n = next();
        while (isWhiteSpace(n))
            n = next();
        while (!isNewLine(n)) {
            sb.append((char) n);
            n = next();
        }
        return sb.toString();
    }

    private static boolean isNewLine(int n) {
        return n == '\n' || n == '\r' || n == -1;
    }

    private static boolean isWhiteSpace(int n) {
        return n == ' ' || isNewLine(n) || n == '\t';
    }

    static int[] nia(int n) throws Exception {
        if (n < 0)
            throw new Exception("Array size should be non negative");
        final int[] array = new int[n];
        for (int i = 0; i < n; ++i)
            array[i] = ni();
        return array;
    }

    static Integer[] __nia__(int n) throws Exception {
        if (n < 0)
            throw new Exception("Array size should be non negative");
        final Integer[] array = new Integer[n];
        for (int i = 0; i < n; ++i)
            array[i] = ni();
        return array;
    }

    static Long[] __nla__(int n) throws Exception {
        if (n < 0)
            throw new Exception("Array size should be non negative");
        final Long[] array = new Long[n];
        for (int i = 0; i < n; ++i)
            array[i] = nl();
        return array;
    }

    static int[][] n2dia(int r, int c) throws Exception {
        if (r < 0 || c < 0)
            throw new Exception("Array size should be non negative");
        int[][] array = new int[r][c];
        for (int i = 0; i < r; i++)
            array[i] = nia(c);
        return array;
    }

    static long[] nla(int n) throws Exception {
        if (n < 0)
            throw new Exception("Array size should be non negative");
        long[] array = new long[n];
        for (int i = 0; i < n; i++)
            array[i] = nl();
        return array;
    }

    static float[] nfa(int n) throws Exception {
        if (n < 0)
            throw new Exception("Array size should be non negative");
        float[] array = new float[n];
        for (int i = 0; i < n; i++)
            array[i] = nl();
        return array;
    }

    static double[] nda(int n) throws Exception {
        if (n < 0)
            throw new Exception("Array size should be non negative");
        double[] array = new double[n];
        for (int i = 0; i < n; i++)
            array[i] = nl();
        return array;
    }

    static <T> void print(T str) {
        try {
            printerBW.append(str.toString());
        } catch (IOException e) {
            System.out.println(e);
        }
        if (HABLA) flush();
    }

    static <T> void println() {
        try {
            printerBW.append('\n');
        } catch (IOException e) {
            System.out.println(e);
        }
        if (HABLA) flush();
    }

    static <T> void println(T str) {
        try {
            if (str == null) {
                printerBW.append("null\n");
            } else {
                printerBW.append(str.toString());
                printerBW.append('\n');
                if (HABLA) flush();
            }
        } catch (IOException e) {
            System.out.println(e);
        }
    }

    public static final String ANSI_RESET = "\u001B[0m";
    public static final String ANSI_DEBUG = "\u001B[33m";
    static <T> void debugl(T str) {
        if (!HABLA) return;
        try {
            if (str == null) {
                printerBW.append(ANSI_DEBUG);
                printerBW.append("null");
                printerBW.append(ANSI_RESET);
            } else {
                printerBW.append(ANSI_DEBUG);
                printerBW.append(str.toString());
                printerBW.append(ANSI_RESET);
            }
        } catch (IOException e) {
            System.out.println(e);
        }
        flush();
    }

    static void debug() {
        if (!HABLA) return;
        try {
            printerBW.append('\n');
        } catch (IOException e) {
            System.out.println(e);
        }
        flush();
    }
    static <T> void debug(T str) {
        if (!HABLA) return;
        try {
            if (str == null) {
                printerBW.append(ANSI_DEBUG);
                printerBW.append("null\n");
                printerBW.append(ANSI_RESET);
            } else {
                printerBW.append(ANSI_DEBUG);
                printerBW.append(str.toString());
                printerBW.append(ANSI_RESET);
                printerBW.append('\n');
            }
        } catch (IOException e) {
            System.out.println(e);
        }
        flush();
    }

    static void flush() {
        try {
            printerBW.flush();
        } catch (IOException e) {
            System.out.println(e);
        }
    }

    static void close() {
        try {
            printerBW.close();
        } catch (IOException e) {
            System.out.println(e.toString());
        }
    }
}