s = eval(input())

if s == "ABC":

    print("ARC")

    

elif s == "ARC":

    print("ABC")
s = eval(input())

if s == "ABC":

    print("ARC")

else:

    print("ABC")
s = eval(input())
if s == "ABC":
    print("ARC")
elif s == "ARC":
    print("ABC")

s = eval(input())
if s == "ABC":
    print("ARC")
else:
    print("ABC")

-elif s == "ARC": +else: