import java.io.PrintStream;
import java.io.PrintWriter;
import java.util.Scanner;


public class Main_yukicoder331 {

	static Scanner sc;
	static Printer pr;
    static boolean[][] used;
    static int[] dx = {0, 1, 0, -1};
    static int[] dy = {1, 0, -1, 0};

    public static void main(String[] args) {
        sc = new Scanner(System.in);
        pr = new Printer(System.out);

        used = new boolean[60][60];

        @SuppressWarnings("unused")
		String s = sc.nextLine();

        dfs(30, 30, 0);

        sc.close();
    }

    private static void dfs(int x, int y, int d) {
    	used[x][y] = true;
    	for (int i = 0; i < 4; i++) {
    		int tmp = go("R");
    		if (tmp == 0) {
    			continue;
    		}

    		int tmpx = x + dx[(d + i + 1) % 4];
    		int tmpy = y + dy[(d + i + 1) % 4];
    		int tmpd = (d + i + 1) % 4;

    		if (!used[tmpx][tmpy]) {
    			go("F");
    			dfs(tmpx, tmpy, tmpd);
    			go("B");
    		}
    	}
	}

	static int go(String cmd) {
    	pr.println(cmd);
    	pr.flush();

    	String s = sc.nextLine();

    	if (s.equals("Merry Christmas!")) {
    		System.exit(0);
    	}

    	int f = Integer.parseInt(s);
    	while (f == 20151224) {
    		go("F");
    	}

    	return f;
    }

    /*
	@SuppressWarnings("unused")
	private static class Scanner {
		BufferedReader br;
		Iterator<String> it;

		Scanner (InputStream in) {
			br = new BufferedReader(new InputStreamReader(in));
		}

		String next() throws RuntimeException  {
			try {
				if (it == null || !it.hasNext()) {
					it = Arrays.asList(br.readLine().split(" ")).iterator();
				}
				return it.next();
			} catch (IOException e) {
				throw new IllegalStateException();
			}
		}

		int nextInt() throws RuntimeException {
			return Integer.parseInt(next());
		}

		long nextLong() throws RuntimeException {
			return Long.parseLong(next());
		}

		float nextFloat() throws RuntimeException {
			return Float.parseFloat(next());
		}

		double nextDouble() throws RuntimeException {
			return Double.parseDouble(next());
		}

		void close() {
			try {
				br.close();
			} catch (IOException e) {
//				throw new IllegalStateException();
			}
		}
	}
	*/

	private static class Printer extends PrintWriter {
		Printer(PrintStream out) {
			super(out);
		}
	}
}