Catherine has a deck of n cards, each of which is either red, green, or blue. As long as there are at least two cards left, she can do one of two actions: 

  * take any two (not necessarily adjacent) cards with different colors and exchange them for a new card of the third color; 
  * take any two (not necessarily adjacent) cards with the same color and exchange them for a new card with that color. 



She repeats this process until there is only one card left. What are the possible colors for the final card?

Input

The first line of the input contains a single integer n (1 ≤ n ≤ 200) — the total number of cards.

The next line contains a string s of length n — the colors of the cards. s contains only the characters 'B', 'G', and 'R', representing blue, green, and red, respectively.

Output

Print a single string of up to three characters — the possible colors of the final card (using the same symbols as the input) in alphabetical order.

Examples

Input

2
RB


Output

G


Input

3
GRG


Output

BR


Input

5
BBBBB


Output

B

Note

In the first sample, Catherine has one red card and one blue card, which she must exchange for a green card.

In the second sample, Catherine has two green cards and one red card. She has two options: she can exchange the two green cards for a green card, then exchange the new green card and the red card for a blue card. Alternatively, she can exchange a green and a red card for a blue card, then exchange the blue card and remaining green card for a red card.

In the third sample, Catherine only has blue cards, so she can only exchange them for more blue cards.
/*
ID: davidzh8
PROG: subset
LANG: JAVA
 */

import java.io.*;
import java.util.*;
import java.lang.*;

public class card {
    //Start Stub
    static long startTime = System.nanoTime();
    //Globals Go Here

    //Globals End
    public static void main(String[] args) throws IOException {
        FastScanner sc = new FastScanner("card.in", true);
        FastWriter pw = new FastWriter("card.out", true);
        int N= sc.ni();
        String line= sc.nextLine();
        int numofR=0;
        int numofB=0;
        int numofG=0;
        for (int i = 0; i < line.length(); i++) {
            if (line.charAt(i)=='R')numofR++;
            if (line.charAt(i)=='B')numofB++;
            if (line.charAt(i)=='G')numofG++;
        }
        if (numofR==0){
            if(numofB==0){
                System.out.println("G");
            }
           else if (numofB>=1 && numofG==0){
                System.out.println("B");
            }

            else if (numofB==1 && numofG==1){
                System.out.println("R");
            }
            else if (numofB>1 && numofG==1){
                System.out.println("GR");
            }
            else if (numofB==1 && numofG>1){
                System.out.println("BR");
            }
            else System.out.println("BGR");
        }
        else if (numofR==1){
            if(numofB==0){
                if (numofG==0) System.out.println("R");
                else if (numofG==1)System.out.println("B");
                else System.out.println("BR");
            }
            else if(numofB==1){
                if(numofG==0){
                    System.out.println("G");
                }
                else System.out.println("BGR");
            }
            else{
                if (numofG==0)System.out.println("GR");
                else System.out.println("BGR");
            }
        }
        else{
            if(numofB==0){
                if (numofG==0) System.out.println("R");
               else if (numofG==1)System.out.println("BG");
                else System.out.println("BGR");
            }
            else if(numofB==1){
                if(numofG==0){
                    System.out.println("BG");
                }
                else System.out.println("BGR");
            }
            else System.out.println("BGR");
        }






        /* End Stub */
        long endTime = System.nanoTime();
        //System.out.println("Execution Time: " + (endTime - startTime) / 1e9 + " s");
        pw.close();
    }


    static class Edge implements Comparable<Edge> {
        int w;
        int a;
        int b;

        public Edge(int w, int a, int b) {
            this.w = w;
            this.a = a;
            this.b = b;

        }

        public int compareTo(Edge obj) {
            if (obj.w == w) {
                if (obj.a == a) {
                    return b - obj.b;
                }
                return a - obj.a;
            } else return w - obj.w;
        }
    }

    static class Pair implements Comparable<Pair> {
        int a;
        int b;

        public Pair(int a, int b) {
            this.a = a;
            this.b = b;
        }

        public int compareTo(Pair obj) {
            if (obj.a == a) {
                return b - obj.b;
            } else return a - obj.a;
        }
    }

    static class SegmentTree {
        public long[] arr;
        public long[] tree;
        public int N;

        //Zero initialization
        public SegmentTree(int n) {
            N = n;
            arr = new long[N];
            tree = new long[4 * N + 1];
        }

        public long query(int treeIndex, int lo, int hi, int i, int j) {
            // query for arr[i..j]
            if (lo > j || hi < i)
                return 0;
            if (i <= lo && j >= hi)
                return tree[treeIndex];
            int mid = lo + (hi - lo) / 2;

            if (i > mid)
                return query(2 * treeIndex + 2, mid + 1, hi, i, j);
            else if (j <= mid)
                return query(2 * treeIndex + 1, lo, mid, i, j);

            long leftQuery = query(2 * treeIndex + 1, lo, mid, i, mid);
            long rightQuery = query(2 * treeIndex + 2, mid + 1, hi, mid + 1, j);

            // merge query results
            return merge(leftQuery, rightQuery);
        }

        public void update(int treeIndex, int lo, int hi, int arrIndex, long val) {
            if (lo == hi) {
                tree[treeIndex] = val;
                arr[arrIndex] = val;
                return;
            }

            int mid = lo + (hi - lo) / 2;

            if (arrIndex > mid)
                update(2 * treeIndex + 2, mid + 1, hi, arrIndex, val);
            else if (arrIndex <= mid)
                update(2 * treeIndex + 1, lo, mid, arrIndex, val);

            // merge updates
            tree[treeIndex] = merge(tree[2 * treeIndex + 1], tree[2 * treeIndex + 2]);
        }

        public long merge(long a, long b) {
            return (a + b);
        }
    }

    static class djset {
        int N;
        int[] parent;

        // Creates a disjoint set of size n (0, 1, ..., n-1)
        public djset(int n) {
            parent = new int[n];
            N = n;
            for (int i = 0; i < n; i++)
                parent[i] = i;
        }

        public int find(int v) {

            // I am the club president!!! (root of the tree)
            if (parent[v] == v) return v;

            // Find my parent's root.
            int res = find(parent[v]);

            // Attach me directly to the root of my tree.
            parent[v] = res;
            return res;
        }

        public boolean union(int v1, int v2) {

            // Find respective roots.
            int rootv1 = find(v1);
            int rootv2 = find(v2);

            // No union done, v1, v2 already together.
            if (rootv1 == rootv2) return false;

            // Attach tree of v2 to tree of v1.
            parent[rootv2] = rootv1;
            return true;
        }


    }

    static class FastScanner {
        public BufferedReader br;
        public StringTokenizer st;
        public InputStream is;

        public FastScanner(String name, boolean debug) throws IOException {
            if (debug) {
                is = System.in;
            } else {
                is = new FileInputStream(name);
            }
            br = new BufferedReader(new InputStreamReader(is), 32768);
            st = null;
        }


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

        public int ni() {
            return Integer.parseInt(next());
        }

        public long nl() {
            return Long.parseLong(next());
        }

        public double nd() {
            return Double.parseDouble(next());
        }

        public String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
            return str;
        }
    }

    static class FastWriter {
        public PrintWriter pw;

        public FastWriter(String name, boolean debug) throws IOException {
            if (debug) {
                pw = new PrintWriter(System.out);
            } else {
                pw = new PrintWriter(new BufferedWriter(new FileWriter(new File(name))));
            }
        }

        public void println(Object text) {
            pw.println(text);
        }

        public void print(Object text) {
            pw.print(text);
        }

        public void close() {
            pw.close();
        }

        public void flush() {
            pw.flush();
        }
    }

}