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.BufferedWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.InputMismatchException;

public class first {
	static long MOD = 1000000007;
	static boolean b[];
	static ArrayList<Integer>[] amp;
	static long sum[],arr[];
	static long ans = 0;
	static FasterScanner sc = new FasterScanner();
	public static void main(String[] args) throws IOException {
		BufferedWriter log = new BufferedWriter(new OutputStreamWriter(System.out));
		int n = sc.nextInt(), k = sc.nextInt(), a = sc.nextInt(), b = sc.nextInt();
		int min=Math.min(a, b);
		int max=Math.max(a, b);
		if(1L*(min+1)*k<max){
			log.write("NO");
		}
		else{
			int a1=max/(min+1);
			int lf=max%(min+1);
			StringBuilder chunk=new StringBuilder();
			for(int i=0;i<a1;i++){
				chunk.append("G");
			}
			StringBuilder sb=new StringBuilder();
			for(int i=0;i<min;i++){
				sb.append(chunk);
				if(i<lf)
					sb.append("G");
				sb.append("B");
			}
			sb.append(chunk);
			if(max==a){
				log.write(sb.toString());
			}
			else{
				for(int i=0;i<sb.length();i++){
					if(sb.charAt(i)=='G'){
						log.write("B");
					}
					else{
						log.write("G");
					}
				}
			}
		}
		log.close();
	}
	public static String cyclicShift(String str){
		char ch[]  = str.toCharArray();
		char temp = ch[0];
		for(int i = 1; i<str.length();i++){
			char temp2 = ch[i];
			ch[i] = temp;
			temp = temp2;
		}
		ch[0] = temp;
		return new String(ch);
	}
	public static void buildGraph(int n){
		for(int i =0;i<n;i++){
			int x = sc.nextInt(), y = sc.nextInt();
			amp[--x].add(--y);
			amp[y].add(x);
		}
	}
	public static void dfs(int x){
		b[x] = true;
		for(int i =0 ;i<amp[x].size();i++){
			if(!b[amp[x].get(i)]){
				dfs(amp[x].get(i));
				sum[x]+=sum[amp[x].get(i)];
			}
		}
		sum[x]+=arr[x];
	}
	public static void dfs2(int x){
		for(int i = 0;i<amp[x].size();i++){
			dfs(amp[x].get(i));
		}
		if(amp[x].size()>=2){
			for(int i = 0;i<amp[x].size();i++){
				dfs(amp[x].get(i));
			}
		}
	}
	public static void seive(int n){
		b = new boolean[(n+1)];
		Arrays.fill(b, true);
		b[0]= false;
		b[1] = false;
		for(int i = 2;i*i<=n;i++){
			if(b[i]){
				for(int p = 2*i;p<=n;p+=i){
					b[p] = false;
				}
			}
		}
	}
	static long modInverse(long a, long mOD2){
	            return  power(a, mOD2-2, mOD2);
	}
	static long power(long x, long y, long m)
	{
	    if (y == 0)
	        return 1;
	    long p = power(x, y/2, m) % m;
	    p = (p * p) % m;
	 
	    return (y%2 == 0)? p : (x * p) % m;
	}
	static long d,x,y;
	public static void extendedEuclidian(long a, long b){
		if(b == 0) {
	        d = a;
	        x = 1;
	        y = 0;
	    }
	    else {
	        extendedEuclidian(b, a%b);
	        int temp = (int) x;
	        x = y;
	        y = temp - (a/b)*y;
	    }
	}
	public static long inverseModulo(long n){
		return powerModulo(n, MOD-2);
	}
	public static long gcd(long n, long m){
		if(m!=0) return gcd(m,n%m);
		else return n;
	}
	public static long powerModulo(long x, long y){
		long ans = 1;
		while(y>0){
			if(y%2==1){
				ans = (ans%MOD*x%MOD)%MOD;
				y--;
			}
			else{
				x = (x%MOD*x%MOD)%MOD;
				y/=2;
			}
		}
	return ans;
	}
	static class Pair implements Comparable<Pair> {
		int u;
		int v;
		public Pair(){
			
		}
		public Pair(int u, int v) {
			this.u = u;
			this.v = v;
		}
		
		public int hashCode() {
			int hu = (int) (u ^ (u >>> 32));
			int hv = (int) (v ^ (v >>> 32));
			return 31*hu + hv;
		}

		public boolean equals(Object o) {
			Pair other = (Pair) o;
			return (u == other.u && v == other.v);
		}

		public int compareTo(Pair other) {
			return Integer.compare(u, other.u) != 0 ? (Integer.compare(u, other.u)) : (Integer.compare(v, other.v));
		}

		public String toString() {
			return "[u=" + u + ", v=" + v + "]";
		}
	}
	public static class FasterScanner {
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;
 
		public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = System.in.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}
 
		public String nextLine() {
			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 String nextString() {
			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 long nextLong() {
			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 int nextInt() {
			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 int[] nextIntArray(int n) {
	        return nextIntArray(n, 0);
	    }
	    
	    public int[] nextIntArray(int n, int off) {
	    	int[] arr = new int[n + off];
	    	for (int i = 0; i < n; i++) {
	    		arr[i + off] = nextInt();
	    	}
	    	return arr;
	    }
	    
	    public long[] nextLongArray(int n) {
	    	return nextLongArray(n, 0);
	    }
        
		public long[] nextLongArray(int n, int off) {
		    long[] arr = new long[n + off];
		    for (int i = 0; i < n; i++) {
		        arr[i + off] = nextLong();
		    }
		    return arr;
		}
 
	    private boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}
 
		private boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}
	}
}