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.*;
/**
 *
 * @author Sourav Kumar Paul (spaul100)
 * NIT Silchar    
 */

public class SOlveD {

    public static Reader in;
    public static PrintWriter out;
    public static long mod = 1000000007;
    public static long inf = 100000000000000000l;
    public static long fac[],inv[];
    public static int union[];

    public static void solve(){
        int n = in.nextInt();
        int k = in.nextInt();
        int a = in.nextInt();
        int b = in.nextInt();
        int x = Math.max(a,b);
        int y = Math.min(a, b);
       //String ans ="";
        char el[] =new char[2];
        if(a>=b)
        {
            el[0] = 'G';
            el[1] = 'B';
        }
        else
        {
            el[0] = 'B';
            el[1] = 'G';
        }
        boolean flag = true;
        char ans[] = new char[n];
        int ctr = 0;
        while(x>=0 && y>=0)
        {
            if(x<=y)
            {
                x--;
                if(x<0)
                    break;
                ans[ctr++] = el[0];
            //    ans += el[0];
            }
            else
            {
                int temp = Math.min(x,k);
                for(int i=0; i<temp; i++)
                 ans[ctr++] = el[0];
                x-=temp;
            }
           // out.println(ans);
            int tt = x;
            x = y;
            y = tt;
            swap(el);
        }
        if(ctr <n)
            out.println("NO");
        else
            out.println(ans);
    }

    private static void swap(char[] el) {
      
        char ss = el[0];
        el[0] = el[1];
        el[1] =ss;
    }

/**
 *  ############################### Template ################################
 */
    

    public static class Pair implements Comparable{
        int x,y;
       
        Pair(int x, int y)
        {
            this.x = x;
            this.y = y;
        }
        @Override
        public int compareTo(Object o)
        {
            Pair pp = (Pair)o;
            if(pp.x == x)
                return 0;
            else if (x>pp.x)
                return 1;
            else 
                return -1;
        }
    }

   
    public static void init()
    {
        for(int i=0; i<union.length; i++)
            union[i] = i;
    }
    public static int find(int n)
    {
        return (union[n]==n)?n:(union[n]=find(union[n]));
    }
    public static void unionSet(int i ,int j)
    {
        union[find(i)]=find(j);
    }
    public static boolean connected(int i,int j)
    {   
        return union[i]==union[j];
    }

    public static long gcd(long a, long b) {
        long x = Math.min(a,b);
        long y = Math.max(a,b);
        while(x!=0)
        {
            long temp = x;
            x = y%x;
            y = temp;
        }
        return y;       
    }

    public static long modPow(long base, long exp, long mod) {
        base = base % mod;
        long result =1;
        while(exp > 0)
        {
            if(exp % 2== 1)
            {
                result = (result * base) % mod;
                exp --;
            }
            else
            {
                base = (base * base) % mod;
                exp = exp >> 1;
            }
            
        }
        return result;
    }
    
    public static void cal()
    {
        fac = new long[1000005];
        inv = new long[1000005];
        fac[0]=1;
        inv[0]=1;
        for(int i=1; i<=1000000; i++)
        {
            fac[i]=(fac[i-1]*i)%mod;
            inv[i]=(inv[i-1]*modPow(i,mod-2,mod))%mod;
        }
    }
    public static long ncr(int n, int r)
    {
        return (((fac[n]*inv[r])%mod)*inv[n-r])%mod;
    }


    SOlveD() throws IOException {
	in = new Reader(new InputStreamReader(System.in));
        out = new PrintWriter(new OutputStreamWriter(System.out));
	solve();
        out.flush();
	out.close();
    }
 
    public static void main(String args[]) {
	new Thread(null, new Runnable() {
            public void run() {
                try {
                    new SOlveD();
		} catch (Exception e) {
                    e.printStackTrace();
		}
            }
	}, "1", 1 << 26).start();
    }
    
    public static class Reader {
        public BufferedReader reader;
        public StringTokenizer st;

        public Reader(InputStreamReader stream) {
            reader = new BufferedReader(stream);
            st = null;
        }

        public String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return st.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }
        public String nextLine() throws IOException{
            return reader.readLine();
        }
        public long nextLong(){
            return Long.parseLong(next());
        }
        public double nextDouble(){
            return Double.parseDouble(next());
        }

    }
}

