import sys
flush = sys.stdout.flush
used = [[0]*50 for i in range(50)]
dx = [-1, 0, 1, 0]
dy = [0, -1, 0, 1]
r4 = range(4)

def dfs(x, y, di):
    for k in r4:
        s = raw_input()
        if s[0]=="M": exit(0)
        d = int(s)
        nd = (di + k) % 4
        nx = x + dx[nd]; ny = y + dy[nd]
        if d and not used[ny][nx]:
            print"F"; flush()
            used[ny][nx] = 1
            dfs(nx, ny, nd)
            input()
        print"R"; flush()
    input()
    print"B"; flush()
used[0][0] = 1
dfs(0, 0, 0)