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

public class Stack2 {

    static class Reader {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;

        public Reader() {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public Reader(String file_name) throws IOException {
            din = new DataInputStream(new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public String readLine() throws IOException {
            byte[] buf = new byte[64]; // line length
            int cnt = 0, c;
            while ((c = read()) != -1) {
                if (c == '\n')
                    break;
                buf[cnt++] = (byte) c;
            }
            return new String(buf, 0, cnt);
        }

        public int nextInt() throws IOException {
            int ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public long nextLong() throws IOException {
            long ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public double nextDouble() throws IOException {
            double ret = 0, div = 1;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');
            if (c == '.') {
                while ((c = read()) >= '0' && c <= '9') {
                    ret += (c - '0') / (div *= 10);
                }
            }
            if (neg)
                return -ret;
            return ret;
        }

        private void fillBuffer() throws IOException {
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }

        private byte read() throws IOException {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }

        public void close() throws IOException {
            if (din == null)
                return;
            din.close();
        }
    }

    static Reader sc = new Reader();
    static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

    public static void main(String[] args) throws IOException {
        /*
         * For integer input: int n=inputInt();
         * For long input: long n=inputLong();
         * For double input: double n=inputDouble();
         * For String input: String s=inputString();
         * Logic goes here
         * For printing without space: print(a+""); where a is a variable of any datatype
         * For printing with space: printSp(a+""); where a is a variable of any datatype
         * For printing with new line: println(a+""); where a is a variable of any datatype
         */
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        String s = sc.next();
        Map<Character, Long> map = new HashMap<>();
        map.put('R',0L);
        map.put('G',0L);
        map.put('B',0L);
        for(int j=0;j<s.length();j++){
            char ch=s.charAt(j);
            map.put(ch,map.get(ch)+1);
        }
        if(map.get('B')>=1&&map.get('G')>=1&&map.get('R')>=1){
            System.out.println("BGR");
        }else if(map.get('B')==0 && map.get('G')>=1&&map.get('R')>=1){
            if(map.get('G')>=2&&map.get('R')>=2){
                System.out.println("BGR");
            }else if(map.get('G')==1){
                if(map.get('R')>=2){
                    System.out.println("BG");
                }else {
                    System.out.println("B");
                }
            }else {
                if(map.get('G')>=2){
                    System.out.println("BR");
                }else {
                    System.out.println("B");
                }
            }
        }else if(map.get('G')==0 && map.get('B')>=1&&map.get('R')>=1){
            if(map.get('B')>=2&&map.get('R')>=2){
                System.out.println("BGR");
            }else if(map.get('B')==1){
                if(map.get('R')>=2){
                    System.out.println("BG");
                }else {
                    System.out.println("G");
                }
            }else {
                if(map.get('B')>=2){
                    System.out.println("GR");
                }else {
                    System.out.println("G");
                }
            }
        }else if(map.get('R')==0 && map.get('B')>=1&&map.get('G')>=1){
            if(map.get('B')>=2&&map.get('G')>=2){
                System.out.println("BGR");
            }else if(map.get('B')==1){
                if(map.get('G')>=2){
                    System.out.println("BR");
                }else {
                    System.out.println("R");
                }
            }else {
                if(map.get('B')>=2){
                    System.out.println("GR");
                }else {
                    System.out.println("R");
                }
            }
        }else {
            long sum=map.get('B')+map.get('G')+map.get('R');
            if(sum==map.get('B')){
                System.out.println("B");
            }else if(sum==map.get('G')){
                System.out.println("G");
            }else {
                System.out.println("R");
            }
        }
        //System.out.println(map);



        bw.flush();
        bw.close();


    }

    public static int query(int l, int r, Scanner sc) {
        System.out.println("? " + l + " " + r);
        return sc.nextInt();

    }

    public static int getAns(int n) {
        if (n >= 1 && n <= 9) {
            return n;
        } else {
            int f = n;
            int c = 0;
            int d = 0;
            while (f != 0) {
                c++;
                d = f % 10;
                f /= 10;

            }
            // int y= (int) (n/(Math.pow(10,c-1)));
            StringBuilder stringBuilder = new StringBuilder();
            for (int j = 1; j <= c; j++) {
                stringBuilder.append(d);
            }
            int ynum = Integer.parseInt(stringBuilder.toString());
            if (n >= ynum) {
                return 1 + getAns(ynum - 1);
            } else {
                if (d == 1) {
                    StringBuilder stringBuilder1 = new StringBuilder();
                    for (int j = 1; j <= c - 1; j++) {
                        stringBuilder1.append(9);
                    }
                    int ynum1 = Integer.parseInt(stringBuilder1.toString());
                    return getAns(ynum1);
                } else {
                    StringBuilder stringBuilder1 = new StringBuilder();
                    for (int j = 1; j <= c; j++) {
                        stringBuilder1.append((d - 1));
                    }
                    int ynum1 = Integer.parseInt(stringBuilder1.toString());
                    return getAns(ynum1);
                }
            }
        }
    }

    public static void bfs(int r, int c, Queue<int[]> queue, long[][] dis, char[][] map, boolean[][] visited) {
        while (!queue.isEmpty()) {
            int[] ar = queue.poll();
            int x = ar[0];
            int y = ar[1];
            if (x + 1 < r) {
                if (map[x + 1][y] != 'T' && dis[x + 1][y] > (dis[x][y] + 1)) {
                    dis[x + 1][y] = Math.min(dis[x + 1][y], (dis[x][y] + 1));
                    queue.add(new int[]{x + 1, y});
                } /*else if (map[x][y] != map[x + 1][y] && dis[x + 1][y] > (dis[x][y] + 1)) {
                    dis[x + 1][y] = Math.min(dis[x + 1][y], dis[x][y] + 1);
                    queue.add(new int[]{x + 1, y});
                }*/
              /*  if(!visited[x+1][y] ){
                    queue.add(new int[]{x + 1, y});
                    visited[x+1][y]=true;
                }*/


            }
            if (y + 1 < c) {
                if (map[x][y + 1] != 'T' && dis[x][y + 1] > (dis[x][y] + 1)) {
                    dis[x][y + 1] = Math.min(dis[x][y + 1], dis[x][y] + 1);
                    queue.add(new int[]{x, y + 1});
                } /*else if (map[x][y] != map[x][y + 1] && dis[x][y + 1] > (dis[x][y] + 1)) {
                    dis[x][y + 1] = Math.min(dis[x][y + 1], dis[x][y] + 1);
                    queue.add(new int[]{x, y + 1});
                }*/
               /* if( !visited[x][y+1]){
                    queue.add(new int[]{x, y+1});
                    visited[x][y+1]=true;
                }*/


            }
            if (x - 1 >= 0) {
                if (map[x - 1][y] != 'T' && dis[x - 1][y] > (dis[x][y] + 1)) {
                    dis[x - 1][y] = Math.min(dis[x - 1][y], (dis[x][y] + 1));
                    queue.add(new int[]{x - 1, y});
                } /*else if (map[x][y] != map[x - 1][y] && dis[x - 1][y] > (dis[x][y] + 1)) {
                    dis[x - 1][y] = Math.min(dis[x - 1][y], dis[x][y] + 1);
                    queue.add(new int[]{x - 1, y});
                }*/
               /* if(!visited[x-1][y]){
                    queue.add(new int[]{x - 1, y});
                    visited[x-1][y]=true;
                }*/


            }
            if (y - 1 >= 0) {
                if (map[x][y - 1] != 'T' && dis[x][y - 1] > (dis[x][y] + 1)) {
                    dis[x][y - 1] = Math.min(dis[x][y - 1], (dis[x][y] + 1));
                    queue.add(new int[]{x, y - 1});
                } /*else if (map[x][y] != map[x][y - 1] && dis[x][y - 1] > (dis[x][y] + 1)) {
                    dis[x][y - 1] = Math.min(dis[x][y - 1], dis[x][y] + 1);
                    queue.add(new int[]{x, y - 1});
                }*/
               /* if(!visited[x][y-1]){
                    queue.add(new int[]{x , y-1});
                    visited[x][y-1]=true;
                }*/


            }
        }
    }


    public static void dfs1(List<List<Integer>> g, boolean[] visited, Stack<Integer> stack, int num) {
        visited[num] = true;
        for (Integer integer : g.get(num)) {
            if (!visited[integer]) {
                dfs1(g, visited, stack, integer);
            }
        }
        stack.push(num);
    }

    public static void dfs2(List<List<Integer>> g, boolean[] visited, List<Integer> list, int num, int c, int[] raj) {
        visited[num] = true;

        for (Integer integer : g.get(num)) {
            if (!visited[integer]) {
                dfs2(g, visited, list, integer, c, raj);
            }
        }
        raj[num] = c;
        list.add(num);

    }

    public static int inputInt() throws IOException {
        return sc.nextInt();
    }

    public static long inputLong() throws IOException {
        return sc.nextLong();
    }

    public static double inputDouble() throws IOException {
        return sc.nextDouble();
    }

    public static String inputString() throws IOException {
        return sc.readLine();
    }

    public static void print(String a) throws IOException {
        bw.write(a);
    }

    public static void printSp(String a) throws IOException {
        bw.write(a + " ");
    }

    public static void println(String a) throws IOException {
        bw.write(a + "\n");
    }


    public static long getAns(int[] ar, int c, long[][] dp, int i, int sign) {
        if (i < 0) {
            return 1;
        }

        if (c <= 0) {
            return 1;
        }

        dp[i][c] = Math.max(dp[i][c], Math.max(ar[i] * getAns(ar, c - 1, dp, i - 1, sign), getAns(ar, c, dp, i - 1, 1)));
        return dp[i][c];
    }


    public static long power(long a, long b, long c) {
        long ans = 1;
        while (b != 0) {
            if (b % 2 == 1) {
                ans = ans * a;
                ans %= c;
            }
            a = a * a;
            a %= c;
            b /= 2;
        }
        return ans;
    }

    public static long power1(long a, long b, long c) {
        long ans = 1;
        while (b != 0) {
            if (b % 2 == 1) {
                ans = multiply(ans, a, c);
            }
            a = multiply(a, a, c);
            b /= 2;

        }
        return ans;

    }

    public static long multiply(long a, long b, long c) {
        long res = 0;
        a %= c;
        while (b > 0) {
            if (b % 2 == 1) {
                res = (res + a) % c;
            }
            a = (a + a) % c;
            b /= 2;
        }

        return res % c;

    }

    public static long totient(long n) {
        long result = n;
        for (long i = 2; i * i <= n; i++) {
            if (n % i == 0) {
                //sum=sum+2*i;
                while (n % i == 0) {
                    n /= i;
                    // sum=sum+n;
                }
                result -= result / i;

            }
        }
        if (n > 1) {
            result -= result / n;

        }
        return result;
    }


    public static long gcd(long a, long b) {
        if (b == 0) {
            return a;
        } else {
            return gcd(b, a % b);
        }
    }

    public static boolean[] primes(int n) {
        boolean[] p = new boolean[n + 1];
        p[0] = false;
        p[1] = false;
        for (int i = 2; i <= n; i++) {
            p[i] = true;
        }

        for (int i = 2; i * i <= n; i++) {
            if (p[i]) {
                for (int j = i * i; j <= n; j += i) {
                    p[j] = false;
                }
            }

        }
        return p;
    }

}