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.util.*;
import java.io.*;

/**
 *
 * @author umang
 */

public class D746 {
    
    public static int mod = (int) (1e9+7);

    public static void main(String[] args) {
 
        InputReader in = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);
        
        int n=in.nextInt();
        int k=in.nextInt();
        int a=in.nextInt();
        int b=in.nextInt();
        int x=0;
        int y=0;
        StringBuilder ans=new StringBuilder();
        for(int i=0;i<n;i++){
            if(a>b){
                if(x<k){
                    ans.append('G');
                    a--;
                    x++;
                    y=0;
                }
                else{
                    ans.append('B');
                    b--;
                    y++;
                    x=0;
                }
            }
            else if(b>a){
                if(y<k){
                    ans.append('B');
                    b--;
                    y++;
                    x=0;
                }
                else{
                    ans.append('G');
                    a--;
                    x++;
                    y=0;
                }                
            }
            else{
                if(x==0){
                    ans.append('G');
                    x++;
                    a--;
                    y=0;
                }
                else{
                    ans.append('B');
                    y++;
                    b--;
                    x=0;
                }
            }
        }
        
        if(a<0 || b<0) out.println("NO");
        else out.println(ans);
        
        out.close();
    }
    
    static class Pair{
		int x;
		int y;
		Pair(int x,int y){
			this.x=x;
			this.y=y;
		}
	}
    
    public static class CompareTable implements Comparator{
        public int compare(Object o1,Object o2){
            Pair p1 = (Pair) o1;
            Pair p2 = (Pair) o2;
            
            if(p1.x>p2.x)
                return -1;
            else if(p1.x<p2.x)
                return 1;
            else{
                if(p1.y<p2.y)
                    return -1;
                else if(p1.y>p2.y)
                    return 1;
                else
                    return 0;
            }
        }
    }
    
    public static boolean isPal(String s){
        for(int i=0, j=s.length()-1;i<=j;i++,j--){
                if(s.charAt(i)!=s.charAt(j)) return false;
        }
        return true;
    }
    public static String rev(String s){
		StringBuilder sb=new StringBuilder(s);
		sb.reverse();
		return sb.toString();
    }
    
    public static long gcd(long x,long y){
	if(x%y==0)
		return y;
	else
		return gcd(y,x%y);
    }
    
    public static int gcd(int x,int y){
	if(x%y==0)
		return y;
	else 
		return gcd(y,x%y);
    }
    
    public static long gcdExtended(long a,long b,long[] x){
        
        if(a==0){
            x[0]=0;
            x[1]=1;
            return b;
        }
        long[] y=new long[2];
        long gcd=gcdExtended(b%a, a, y);
        
        x[0]=y[1]-(b/a)*y[0];
        x[1]=y[0];
        
        return gcd;
    }
    
    public static int abs(int a,int b){
	return (int)Math.abs(a-b);
    }

    public static long abs(long a,long b){
	return (long)Math.abs(a-b);
    }
    
    public static int max(int a,int b){
	if(a>b)
		return a;
	else
		return b;
    }

    public static int min(int a,int b){
	if(a>b)
		return b;
	else 
		return a;
    }
    
    public static long max(long a,long b){
	if(a>b)
		return a;
	else
		return b;
    }

    public static long min(long a,long b){
	if(a>b)
		return b;
	else 
		return a;
    }

    public static long pow(long n,long p,long m){
	 long  result = 1;
	  if(p==0)
	    return 1;
	if (p==1)
	    return n;
	while(p!=0)
	{
	    if(p%2==1)
	        result *= n;
	    if(result>=m)
	    result%=m;
	    p >>=1;
	    n*=n;
	    if(n>=m)
	    n%=m;
	}
	return result;
    }
    
    public static long pow(long n,long p){
	long  result = 1;
	  if(p==0)
	    return 1;
	if (p==1)
	    return n;
	while(p!=0)
	{
	    if(p%2==1)
	        result *= n;	    
	    p >>=1;
	    n*=n;	    
	}
	return result;
    }
    
	static class InputReader {

		private final InputStream stream;
		private final byte[] buf = new byte[8192];
		private int curChar, snumChars;
		private SpaceCharFilter filter;

		public InputReader(InputStream stream) {
			this.stream = stream;
		}

		public int snext() {
			if (snumChars == -1)
				throw new InputMismatchException();
			if (curChar >= snumChars) {
				curChar = 0;
				try {
					snumChars = stream.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (snumChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public int nextInt() {
			int c = snext();
			while (isSpaceChar(c)) {
				c = snext();
			}
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = snext();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = snext();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public long nextLong() {
			int c = snext();
			while (isSpaceChar(c)) {
				c = snext();
			}
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = snext();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = snext();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public int[] nextIntArray(int n) {
			int a[] = new int[n];
			for (int i = 0; i < n; i++) {
				a[i] = nextInt();
			}
			return a;
		}

		public long[] nextLongArray(int n) {
			long a[] = new long[n];
			for (int i = 0; i < n; i++) {
				a[i] = nextInt();
			}
			return a;
		}
                
		public String readString() {
			int c = snext();
			while (isSpaceChar(c)) {
				c = snext();
			}
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = snext();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public String nextLine() {
			int c = snext();
			while (isSpaceChar(c))
				c = snext();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = snext();
			} while (!isEndOfLine(c));
			return res.toString();
		}

		public boolean isSpaceChar(int c) {
			if (filter != null)
				return filter.isSpaceChar(c);
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

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

		public interface SpaceCharFilter {
			public boolean isSpaceChar(int ch);
		}
	}
}    

