N=int(input())
seen=set()
def F():
    input()
    print("F")
def B():
    input()
    print("B")
def L():
    input()
    print("L")
def R():
    input()
    print("R")
def solve(x,y):
    seen.add((x,y))
    le=int(input())
    if le and not (x+1,y) in seen:
        print("F")
        solve(x+1,y)
        B()
    L()
    le=int(input())
    if le and not (x,y+1) in seen:
        print("F")
        solve(x,y+1)
        B()
    le=int(input())
    if le and not (x-1,y) in seen:
        print("F")
        solve(x-1,y)
        B()
    le=int(input())
    if le and not (x,y-1) in seen:
        print("F")
        solve(x,y-1)
        B()
print("F")
solve(0,0)