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

/**
 * Author:-Harsh Chaudhari
 * College:-DA-IICT
 */
import java.util.*;
import java.io.*;

public class C746 {

	public static void main(String[] args) {
		InputReader s = new InputReader(System.in);
		PrintWriter out = new PrintWriter(System.out);
		/*My code starts here.*/
		int n = s.nextInt(),k = s.nextInt(),a = s.nextInt(),b = s.nextInt();
		int c = Math.max(a, b),d = Math.min(a, b);
		char c1 = 'B',c2 = 'G';
		if(c==a){
			c1 = 'G';c2 = 'B';
		}
		int k1 = k,k2 = k,d1=d,y = (int)Math.ceil((d*1.0)/k),k3 = k;
		int x = (int)Math.ceil((c*1.0)/k);
		StringBuilder str = new StringBuilder();
		if(x<=(d+1)){
			while(c>0 || d>0){
				y = (int)Math.ceil((d*1.0)/k2);
				x = (int)Math.ceil((c*1.0)/k2);
				if(c>0){
					if(c - (y-1)>=k2){
						k = Math.min(c, k);
						for(int i=0;i<k;i++){
							str.append(c1);
						}
						c-=k;
					}
					else{
						str.append(c1);
						c-=1;
					}
				}
				if(d>0){
					if(d - (x-1)>=k2){
						k1 = Math.min(d	, k1);
						for(int i=0;i<k1;i++)
							str.append(c2);
						d-=k1;
					}
					else{
						str.append(c2);
						d-=1;
					}
					//d-=1;
				}
			}
			out.print(str);
		}
		else
			out.println("NO");
		/*My code ends here.*/
		out.close();
	}

	static long PowerMod(long a, long b, long m) {
		long tempo;
		if (b == 0)
			tempo = 1;
		else if (b == 1)
			tempo = a;
		else {
			long temp = PowerMod(a, b / 2, m);
			if (b % 2 == 0)
				tempo = (temp * temp) % m;
			else
				tempo = ((temp * temp) % m) * a % m;
		}
		return tempo;
	}

	static class Node implements Comparable<Node> {
		int num, freq, idx;

		public Node(int u, int v, int idx) {
			this.num = u;
			this.freq = v;
			this.idx = idx;
		}

		public int compareTo(Node n) {
			if (this.freq == n.freq)
				return Integer.compare(this.num, n.num);
			return Integer.compare(-this.freq, -n.freq);
		}
	}

	static class InputReader {

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

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