using System;
using System.Collections;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;

using E = System.Linq.Enumerable;

internal partial class Solver {

    string Query(IEnumerable<int> A) {
        cout.WriteLine("? " + string.Join(" ", A.Select(x => x + 1)));
        cout.Flush();
        return ns();
    }

    public void Run() {
        var N = ni();
        char[] ans = new char[2 * N];
        if (N == 1) {
            for (int i = 0; i < 2 * N; i++) {
                ans[i] = Query(new[] { i })[0];
            }
        } else {
            var leftColor = Query(E.Range(0, N));
            int current = 0;
            for (int i = (1 << 10); i >= 1; i >>= 1) {
                var next = current + i;
                if (N <= next) continue;
                var color = Query(E.Range(next, N));
                if (color == leftColor) {
                    current = next;
                }
            }
            // current, current+1
            var common = E.Range(current + 1, N - 1).ToArray();
            for (int i = 0; i < 2 * N; i++) {
                if (common.Contains(i)) continue;
                var color = Query(common.Concat(new[] { i }));
                ans[i] = color[0];
            }

            var otherR = new List<int>();
            var otherB = new List<int>();

            for (int i = 0; i < 2 * N; i++) {
                if (ans[i] == 'R' && otherR.Count + 1 <= N / 2) {
                    otherR.Add(i);
                } else if (ans[i] == 'B' && otherB.Count + 1 <= N / 2) {
                    otherB.Add(i);
                }
            }
            common = otherR.Concat(otherB).ToArray();
            if (common.Length == N - 1) {
                for (int i = 0; i < 2 * N; i++) {
                    if (ans[i] != 0) continue;
                    if (common.Contains(i)) continue;
                    var color = Query(common.Concat(new[] { i }));
                    ans[i] = color[0];
                }
            }
        }
        var r = ans.Count(c => c == 'R');
        var b = ans.Count(c => c == 'B');

        if (r == N) {
            for (int i = 0; i < ans.Length; i++) {
                if (ans[i] == 0) ans[i] = 'B';
            }
        }
        if (b == N) {
            for (int i = 0; i < ans.Length; i++) {
                if (ans[i] == 0) ans[i] = 'R';
            }
        }

        cout.WriteLine("! " + new string(ans));
        cout.Flush();
    }
}

// PREWRITEN CODE BEGINS FROM HERE
internal partial class Solver : Scanner {
    public static void Main(string[] args) {
#if LOCAL
        byte[] inputBuffer = new byte[1000000];
        var inputStream = Console.OpenStandardInput(inputBuffer.Length);
        Console.SetIn(new StreamReader(inputStream, Console.InputEncoding, false, inputBuffer.Length));
        new Solver(Console.In, Console.Out).Run();
#else
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        new Solver(Console.In, Console.Out).Run();
        Console.Out.Flush();
#endif
    }

#pragma warning disable IDE0052
    private readonly TextReader cin;
    private readonly TextWriter cout;
#pragma warning restore IDE0052

    public Solver(TextReader reader, TextWriter writer)
        : base(reader) {
        cin = reader;
        cout = writer;
    }
    public Solver(string input, TextWriter writer)
        : this(new StringReader(input), writer) {
    }

#pragma warning disable IDE1006
#pragma warning disable IDE0051
    private int ni() { return NextInt(); }
    private int[] ni(int n) { return NextIntArray(n); }
    private long nl() { return NextLong(); }
    private long[] nl(int n) { return NextLongArray(n); }
    private double nd() { return NextDouble(); }
    private double[] nd(int n) { return NextDoubleArray(n); }
    private string ns() { return Next(); }
    private string[] ns(int n) { return NextArray(n); }
#pragma warning restore IDE1006
#pragma warning restore IDE0051
}

internal static class LinqPadExtension {
    public static T Dump<T>(this T obj) {
#if LOCAL
        return LINQPad.Extensions.Dump(obj);
#else
        return obj;
#endif
    }
}

public class Scanner {
    private readonly TextReader Reader;
    private readonly Queue<string> TokenQueue = new Queue<string>();
    private readonly CultureInfo ci = CultureInfo.InvariantCulture;

    public Scanner()
        : this(Console.In) {
    }

    public Scanner(TextReader reader) {
        Reader = reader;
    }

    public int NextInt() { return int.Parse(Next(), ci); }
    public long NextLong() { return long.Parse(Next(), ci); }
    public double NextDouble() { return double.Parse(Next(), ci); }
    public string[] NextArray(int size) {
        string[] array = new string[size];
        for (int i = 0; i < size; i++) {
            array[i] = Next();
        }

        return array;
    }
    public int[] NextIntArray(int size) {
        int[] array = new int[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextInt();
        }

        return array;
    }

    public long[] NextLongArray(int size) {
        long[] array = new long[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextLong();
        }

        return array;
    }

    public double[] NextDoubleArray(int size) {
        double[] array = new double[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextDouble();
        }

        return array;
    }

    public string Next() {
        if (TokenQueue.Count == 0) {
            if (!StockTokens()) {
                throw new InvalidOperationException();
            }
        }
        return TokenQueue.Dequeue();
    }

    public bool HasNext() {
        if (TokenQueue.Count > 0) {
            return true;
        }

        return StockTokens();
    }

    private static readonly char[] _separator = new[] { ' ', '\t' };
    private bool StockTokens() {
        while (true) {
            string line = Reader.ReadLine();
            if (line == null) {
                return false;
            }

            string[] tokens = line.Split(_separator, StringSplitOptions.RemoveEmptyEntries);
            if (tokens.Length == 0) {
                continue;
            }

            foreach (string token in tokens) {
                TokenQueue.Enqueue(token);
            }

            return true;
        }
    }
}


Measured memory_bytes: 15908