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.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class P746D {
  // problem http://codeforces.com/contest/746/problem/D
  InputStream is;
  PrintWriter out;
  // String INPUT = "5 1 3 2";
  // String INPUT = "7 2 2 5";
  // String INPUT = "4 3 4 0";
  String INPUT = "100000 39 24855 75145";
  // String INPUT = "80 5 60 20";

  void solve() {
    int n = ni();
    int k = ni();
    int a = ni();
    int b = ni();
    int[] res = new int[n];
    int[] color = new int[n];
    int len = 0;
    char first = 'G';
    char second = 'B';
    if (a < b) {
      int tmp = a;
      a = b;
      b = tmp;
      first = 'B';
      second = 'G';
    }
    while (a > 0 || b > 0) {
      if (a > 0) {
        int tmp = Math.min(k, a);
        a -= tmp;
        res[len] = tmp;
        color[len] = 1;
        len++;
      } else {
        a--;
        boolean ok = false;
        for (int i = 0; i < len; i++) {
          if (color[i] == 1 && res[i] > 1) {
            res[i]--;
            res[len] = 1;
            color[len] = 1;
            len++;
            ok = true;
            break;
          }
        }
        if (!ok) {
          System.out.println("NO");
          return;
        }
      } 
      if (b > 0) {
        int tmp = Math.min(k, b);
        b -= tmp;
        res[len] = tmp;
        color[len] = 2;
        len++;
      } else {
        if (a == 0) {
          break;
        }
        b--;
        boolean ok = false;
        for (int i = 0; i < len; i++) {
          if (color[i] == 2 && res[i] > 1) {
            res[i]--;
            res[len] = 1;
            color[len] = 2;
            len++;
            ok = true;
            break;
          }
        }
        if (!ok) {
          System.out.println("NO");
          return;
        }
      }
    }
    
    char[] chars = new char[n];
    int pos = 0;
    for (int i = 0; i < len; i++) {
      for (int j = 0; j < res[i]; j++, pos++) {
        chars[pos] = color[i] == 1 ? first : second;
      }
    }
    System.out.println(new String(chars));
  }
  
  public static void main(String[] args) throws Exception {
    new P746D().run();
  }
  
  void run() throws Exception {
    is = oj ? System.in : new ByteArrayInputStream(INPUT.getBytes());
    out = new PrintWriter(System.out);
  
    long s = System.currentTimeMillis();
    solve();
    out.flush();
    tr(System.currentTimeMillis() - s + "ms");
  }
  
  private byte[] inbuf = new byte[1024];
  private int lenbuf = 0, ptrbuf = 0;
  
  private int readByte() {
    if (lenbuf == -1)
      throw new InputMismatchException();
    if (ptrbuf >= lenbuf) {
      ptrbuf = 0;
      try {
        lenbuf = is.read(inbuf);
      } catch (IOException e) {
        throw new InputMismatchException();
      }
      if (lenbuf <= 0)
        return -1;
    }
    return inbuf[ptrbuf++];
  }
  
  private boolean isSpaceChar(int c) {
    return !(c >= 33 && c <= 126);
  }
  
  private int skip() {
    int b;
    while ((b = readByte()) != -1 && isSpaceChar(b))
      ;
    return b;
  }
  
  private double nd() {
    return Double.parseDouble(ns());
  }
  
  private char nc() {
    return (char) skip();
  }
  
  private String ns() {
    int b = skip();
    StringBuilder sb = new StringBuilder();
    while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != ' ')
      sb.appendCodePoint(b);
      b = readByte();
    }
    return sb.toString();
  }
  
  private char[] ns(int n) {
    char[] buf = new char[n];
    int b = skip(), p = 0;
    while (p < n && !(isSpaceChar(b))) {
      buf[p++] = (char) b;
      b = readByte();
    }
    return n == p ? buf : Arrays.copyOf(buf, p);
  }
  
  private char[][] nm(int n, int m) {
    char[][] map = new char[n][];
    for (int i = 0; i < n; i++)
      map[i] = ns(m);
    return map;
  }
  
  private int[] na(int n) {
    int[] a = new int[n];
    for (int i = 0; i < n; i++)
      a[i] = ni();
    return a;
  }
  
  private int ni() {
    int num = 0, b;
    boolean minus = false;
    while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
      ;
    if (b == '-') {
      minus = true;
      b = readByte();
    }
  
    while (true) {
      if (b >= '0' && b <= '9') {
        num = num * 10 + (b - '0');
      } else {
        return minus ? -num : num;
      }
      b = readByte();
    }
  }
  
  private long nl() {
    long num = 0;
    int b;
    boolean minus = false;
    while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
      ;
    if (b == '-') {
      minus = true;
      b = readByte();
    }
  
    while (true) {
      if (b >= '0' && b <= '9') {
        num = num * 10 + (b - '0');
      } else {
        return minus ? -num : num;
      }
      b = readByte();
    }
  }
  
  private boolean oj = System.getProperty("ONLINE_JUDGE") != null;
  
  private void tr(Object... o) {
    if (!oj)
      System.out.println(Arrays.deepToString(o));
  }
}
