import sys
sys.setrecursionlimit(10**7)

N=int(input())
seen=set()

def solve(x,y):
    le=input()
    if le=="Merry Christmas!":
        exit()
    le=int(le)
    if not (x+1,y) in seen:
        if le:
            print("F")
            solve(x+1,y)
            input()
            print("B")

    print("L")
    le=input()
    if le=="Merry Christmas!":
        exit()
    le=int(le)
    if not (x,y+1) in seen:
        if le:
            print("F")
            solve(x,y+1)
            input()
            print("B")

    print("L")
    le=input()
    if le=="Merry Christmas!":
        exit()
    le=int(le)
    if not (x-1,y) in seen:
        if le:
            print("F")
            solve(x-1,y)
            input()
            print("B")
    
    print("L")
    le=input()
    if le=="Merry Christmas!":
        exit()
    le=int(le)
    if not (x,y-1) in seen:
        if le:
            print("F")
            solve(x,y-1)
            input()
            print("B")

print("F")
solve(0,0)