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.text.*;
import java.math.*;
import java.util.regex.*;
import java.lang.*;


public class D{
	static long mod=1000000007;
	
    public static void main(String[] args) throws Exception{           	
    	InputReader in = new InputReader(System.in);       
    	PrintWriter pw=new PrintWriter(System.out);   
    	
    	
    	//int t=in.readInt();
        //while(t-->0)
        //{
    	
        int n=in.readInt();
        int k=in.readInt();
        int a=in.readInt();
        int b=in.readInt();
        char c1='G';
        char c2='B';
        char ans[]=new char[n];
        int f=1;
        StringBuilder sb=new StringBuilder("");
        
        if(a>b)
        {
        	while(true)
        	{
        	int c=1;
        	
        	while(a>b)
            {
        		a--;
            	sb.append(c1);
            	c++;
            	if(c>k)
            		break;
            	
            }
        	if(a==b)
        	{
        		for(int i=1;i<=a;i++)
            		sb.append(c2).append(c1);
        		break;
        	}
        	else
        	{
        		if(b==0)
        		{
        			f=0;
        			break;
        		}
        		else
        		{
        			b--;
        			sb.append(c2);
        		}
        	}
        	}
        }
        else if(a==b)
        {
        	for(int i=1;i<=a;i++)
        		sb.append(c1).append(c2);
        }
        else
        {
        	while(true)
        	{
        	int c=1;
        	
        	while(b>a)
            {
        		b--;
            	sb.append(c2);
            	c++;
            	if(c>k)
            		break;
            	
            }
        	if(a==b)
        	{
        		for(int i=1;i<=a;i++)
            		sb.append(c1).append(c2);
        		break;
        	}
        	else
        	{
        		if(a==0)
        		{
        			f=0;
        			break;
        		}
        		else
        		{
        			a--;
        			sb.append(c1);
        		}
        	}
        	}
        }
        
       
       
        
    	if(f==1)
		{
    		String g=sb.toString();
  
    		pw.println(g);	     	
		}
    	else
    	{
    		pw.println("NO");	     	
    	}
    	
    	//}
    	
    	pw.close();
    }
    

	
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 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 Pair implements Comparable<Pair>
{
	int a,b;
	Pair (int a,int b)
	{
		this.a=a;
		this.b=b;
	}

	public int compareTo(Pair o) {
		// TODO Auto-generated method stub
		if(this.a!=o.a)
		return Integer.compare(this.a,o.a);
		else
			return Integer.compare(this.b, o.b);
		//return 0;
	}
	public boolean equals(Object o) {
        if (o instanceof Pair) {
            Pair p = (Pair)o;
            return p.a == a && p.b == b;
        }
        return false;
    }
    public int hashCode() {
        return new Integer(a).hashCode() * 31 + new Integer(b).hashCode();
    }
    
} 
    
static long sort(int a[])
{  int n=a.length;
	int b[]=new int[n];	
	return mergeSort(a,b,0,n-1);}
static long mergeSort(int a[],int b[],long left,long right)
{ long c=0;if(left<right)
 {   long mid=left+(right-left)/2;
	 c= mergeSort(a,b,left,mid);
	 c+=mergeSort(a,b,mid+1,right);
	 c+=merge(a,b,left,mid+1,right); }	
	return c;	 }
static long merge(int a[],int  b[],long left,long mid,long right)
{long c=0;int i=(int)left;int j=(int)mid; int k=(int)left;
while(i<=(int)mid-1&&j<=(int)right)
{ if(a[i]<=a[j]) {b[k++]=a[i++]; }
else	{ b[k++]=a[j++];c+=mid-i;}}
while (i <= (int)mid - 1)   b[k++] = a[i++]; 
while (j <= (int)right) b[k++] = a[j++];
for (i=(int)left; i <= (int)right; i++) 
	a[i] = b[i];  return c;  }
    
public static int[] radixSort(int[] f)
{
	int[] to = new int[f.length];
	{
		int[] b = new int[65537];
		for(int i = 0;i < f.length;i++)b[1+(f[i]&0xffff)]++;
		for(int i = 1;i <= 65536;i++)b[i]+=b[i-1];
		for(int i = 0;i < f.length;i++)to[b[f[i]&0xffff]++] = f[i];
		int[] d = f; f = to;to = d;
	}
	{
		int[] b = new int[65537];
		for(int i = 0;i < f.length;i++)b[1+(f[i]>>>16)]++;
		for(int i = 1;i <= 65536;i++)b[i]+=b[i-1];
		for(int i = 0;i < f.length;i++)to[b[f[i]>>>16]++] = f[i];
		int[] d = f; f = to;to = d;
	}
	return f;
}    
static  class InputReader
{
    private InputStream stream;
    private byte[] buf = new byte[1024];
    private int curChar;
    private int numChars;
    private SpaceCharFilter filter;

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

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

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

    public interface SpaceCharFilter
    {
        public boolean isSpaceChar(int ch);
    }
    public boolean isEndOfLine(int c) {
        return c == '\n' || c == '\r' || c == -1;
    }
}

  
//BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	//StringBuilder sb=new StringBuilder("");
	 //InputReader in = new InputReader(System.in);
	//PrintWriter pw=new PrintWriter(System.out);
	//String line=br.readLine().trim();
	       	
	//int t=Integer.parseInt(br.readLine());
  //	while(t-->0)
  	//{
  	//int n=Integer.parseInt(br.readLine());
	//long n=Long.parseLong(br.readLine());
	//String l[]=br.readLine().split(" ");
  //int m=Integer.parseInt(l[0]);
	//int k=Integer.parseInt(l[1]);
	//String l[]=br.readLine().split(" ");
	//l=br.readLine().split(" ");
	/*int a[]=new int[n];
	for(int i=0;i<n;i++)
	{
		a[i]=Integer.parseInt(l[i]);
	}*/
	   //System.out.println(" ");	     	
	
	//}
}
