Innokentiy likes tea very much and today he wants to drink exactly n cups of tea. He would be happy to drink more but he had exactly n tea bags, a of them are green and b are black.

Innokentiy doesn't like to drink the same tea (green or black) more than k times in a row. Your task is to determine the order of brewing tea bags so that Innokentiy will be able to drink n cups of tea, without drinking the same tea more than k times in a row, or to inform that it is impossible. Each tea bag has to be used exactly once.

Input

The first line contains four integers n, k, a and b (1 ≤ k ≤ n ≤ 105, 0 ≤ a, b ≤ n) — the number of cups of tea Innokentiy wants to drink, the maximum number of cups of same tea he can drink in a row, the number of tea bags of green and black tea. It is guaranteed that a + b = n.

Output

If it is impossible to drink n cups of tea, print "NO" (without quotes).

Otherwise, print the string of the length n, which consists of characters 'G' and 'B'. If some character equals 'G', then the corresponding cup of tea should be green. If some character equals 'B', then the corresponding cup of tea should be black.

If there are multiple answers, print any of them.

Examples

Input

5 1 3 2


Output

GBGBG


Input

7 2 2 5


Output

BBGBGBB

Input

4 3 4 0


Output

NO
import java.io.*;
import java.util.*;
import java.math.*;

public class D {
    public static void main(String args[]) {
        try {
            InputReader in = new InputReader(System.in);
            BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));
            Vector<Character> res = new Vector<Character>();
            int n = in.readInt();
            int k = in.readInt();
            int a = in.readInt();
            int b = in.readInt();
            boolean ans = true;
            if (a >= b) {
                Vector<Integer> indexb = new Vector<Integer>();
                int ki = 0;
                while(a != 0) {
                    res.add('G'); a--;
                    ki++;
                    if (ki == k && a > 0) {
                        ki = 0;
                        if (b > 0) {
                            res.add('B');
                            indexb.add(res.size() - 1);
                            b--;
                        }
                        else{
                            ans = false;
                        }
                    }
                }
                if(b != 0) {
                    for (int i = 0; i < indexb.size(); i++) {
                        int ib = indexb.get(i);
                        for (int j = 0; j < Math.min(b, k - 1); j++) {
                            res.add(ib, 'B');
                        }
                        b -= Math.min(b, k - 1);
                        if (b == 0) {
                            break;
                        }
                    }
                    if (b != 0) {
                        for (int i = 0; i < k; i++) {
                            res.add(0, 'B');
                            b--;
                            if (b == 0) {
                                break;
                            }
                        }
                        if (res.size() - 1 == 'G') {
                            for (int i = 0; i < k; i++) {
                                res.add(res.size() - 1, 'B');
                                b--;
                                if (b == 0) {
                                    break;
                                }
                            }
                        }
                        if (b != 0) {
                            ans = false;
                        }
                    }
                }
            }
            else {
                int ki = 0;
                Vector<Integer> indexg = new Vector<Integer>();
                while(b != 0) {
                    res.add('B'); b--;
                    ki++;
                    if (ki == k && b > 0) {
                        ki = 0;
                        if (a > 0) {
                            res.add('G');
                            indexg.add(res.size() - 1);
                            a--;
                        }
                        else{
                            ans = false;
                        }
                    }
                }
                if(a != 0) {
                    for (int i = 0; i < indexg.size(); i++) {
                        int ia = indexg.get(i);
                        for (int j = 0; j < Math.min(a, k - 1); j++) {
                            res.add(ia, 'G');
                        }
                        a -= Math.min(a, k - 1);
                        if (a == 0) {
                            break;
                        }
                    }
                    if (a != 0) {
                        for (int i = 0; i < k; i++) {
                            res.add(0, 'G');
                            a--;
                            if (a == 0) {
                                break;
                            }
                        }
                        if (res.size() - 1 == 'B') {
                            for (int i = 0; i < k; i++) {
                                res.add(res.size() - 1, 'G');
                                a--;
                                if (a == 0) {
                                    break;
                                }
                            }
                        }
                        if (a != 0) {
                            ans = false;
                        }
                    }
                }
            }
            if (ans) {
                for (int i = 0; i < res.size(); i++) {
                    out.write(res.get(i));
                }
            }
            else {
                out.write("NO");
            }
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
class InputReader {
    private boolean finished = false;

    private InputStream stream;
    private byte[] buf = new byte[1024];
    private int curChar;
    private int numChars;

    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 peek() {
        if (numChars == -1)
            return -1;
        if (curChar >= numChars) {
            curChar = 0;
            try {
                numChars = stream.read(buf);
            } catch (IOException e) {
                return -1;
            }
            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 String readString() {
        int length = readInt();
        if (length < 0)
            return null;
        byte[] bytes = new byte[length];
        for (int i = 0; i < length; i++)
            bytes[i] = (byte) read();
        try {
            return new String(bytes, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            return new String(bytes);
        }
    }

    public static boolean isSpaceChar(int c) {
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

    private String readLine0() {
        StringBuffer buf = new StringBuffer();
        int c = read();
        while (c != '\n' && c != -1) {
            if (c != '\r')
                buf.appendCodePoint(c);
            c = read();
        }
        return buf.toString();
    }

    public String readLine() {
        String s = readLine0();
        while (s.trim().length() == 0)
            s = readLine0();
        return s;
    }

    public String readLine(boolean ignoreEmptyLines) {
        if (ignoreEmptyLines)
            return readLine();
        else
            return readLine0();
    }

    public BigInteger readBigInteger() {
        try {
            return new BigInteger(readString());
        } catch (NumberFormatException e) {
            throw new InputMismatchException();
        }
    }

    public char readCharacter() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        return (char) c;
    }

    public double readDouble() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        double res = 0;
        while (!isSpaceChar(c) && c != '.') {
            if (c == 'e' || c == 'E')
                return res * Math.pow(10, readInt());
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            res *= 10;
            res += c - '0';
            c = read();
        }
        if (c == '.') {
            c = read();
            double m = 1;
            while (!isSpaceChar(c)) {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, readInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                m /= 10;
                res += (c - '0') * m;
                c = read();
            }
        }
        return res * sgn;
    }

    public boolean isExhausted() {
        int value;
        while (isSpaceChar(value = peek()) && value != -1)
            read();
        return value == -1;
    }

    public String next() {
        return readString();
    }

    public boolean readBoolean() {
        return readInt() == 1;
    }
}

