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 javax.print.DocFlavor;
import java.beans.IntrospectionException;
import java.io.*;
import java.lang.reflect.Array;
import java.util.*;
import java.lang.*;
import static java.lang.Math.*;
public class main implements Runnable {

    public static void main(String[] args) {
        new Thread(null, new main(), "Check2", 1 << 28).start();// to increse stack size in java
    }

    static long mod = (long) (1e9 + 7);

    public void run() {
        InputReader in = new InputReader(System.in);
        PrintWriter w = new PrintWriter(System.out);


        int n=in.nextInt();
        int k=in.nextInt();
        int a=in.nextInt();
        int b=in.nextInt();
        int co1=a;
        int co2=b;
        int p1=0;
        int p2=0;
        StringBuilder ans = new StringBuilder();

        for(int i=0;i<n;i++){
            if(co1>=co2){

                if(p1<k){
                    ans=ans.append("G");
                    p1++;
                    co1--;
                    p2=0;
                }
                else{
                    ans=ans.append("B");
                    p2++;
                    co2--;
                    p1=0;

                }


            }
            else{

               if(p2<k){
                   ans=ans.append("B");
                   p2++;
                   co2--;
                   p1=0;
               }
               else{
                   ans=ans.append("G");
                   p1++;
                   co1--;
                   p2=0;
               }

            }
        }
        if(co1<0||co2<0)w.println("NO");
        else
            w.println(ans);




        w.close();
    }
    static class pair2 implements Comparable<pair2> {

        int a;
        int b;

        pair2(int a, int b) {
            this.a = a;
            this.b = b;

        }

        public int compareTo(pair2 o) {

            if (o.a != this.a) return this.a - o.a;
            else
                return this.b - o.b;


        }

    }

    static void diji(int s, long dist[], ArrayList<pair> adj[]) {
        dist[s] = 0;
        PriorityQueue<pair> q = new PriorityQueue<>(new cmp());
        q.add(new pair(s, 0));
        while (!q.isEmpty()) {
            pair p1 = q.poll();
            for (pair ne : adj[p1.a]) {

                if ((long) p1.b + (long) ne.b < dist[ne.a]) {
                    dist[ne.a] = (long) p1.b + (long) ne.b;
                    pair p2 = new pair(ne.a, dist[ne.a]);
                    q.add(p2);

                }

            }
        }

    }

    static class cmp implements Comparator<pair>{

        public  int compare(pair o1,pair o2)
        {
            return o1.b<o2.b?-1:o1.b>o2.b?1:0;
        }

    }

    static class pair {
        int a;
        long b;
        pair(int a,long b){
            this.a=a;
            this.b=b;
        }
        public boolean equals(Object obj) {      //  override equals method for object to remove tem from arraylist and sets etc.......
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            pair other = (pair) obj;
            if (b!= other.b||a!=other.a)
                return false;
            return true;
        }
    }

    static long modinv(long a,long b)
    {
        long p=power(b,mod-2);

        p=a%mod*p%mod;
        p%=mod;

        return p;

    }

    static long power(long x,long y){
        if(y==0)return 1%mod;
        if(y==1)return x%mod;


        long res=1;
        x=x%mod;
        while(y>0){


            if((y%2)!=0){
                res=(res*x)%mod;
            }


            y=y/2;
            x=(x*x)%mod;
        }


        return res;

    }
    static  long gcd(long a,long b){

        if(b==0)return a;
        return gcd(b,a%b);
    }

    static  void sev(int a[],int n){

        for(int i=2;i<=n;i++)a[i]=i;
        for(int i=2;i<=n;i++){

            if(a[i]!=0){
                for(int j=2*i;j<=n;){

                    a[j]=0;
                    j=j+i;
                }
            }

        }

    }



    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 String nextLine()
        {
            BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        }
        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 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 double nextDouble()
        {
            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, nextInt());
                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, nextInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            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 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);
        }
    }







}
