def main():

    print((list(set(["ABC", "ARC"])-{eval(input())})[0]))

        



if __name__ == "__main__":

    main()
def main():

    s = eval(input())

    if s == "ABC":

        print("ARC")

    else:

        print("ABC")



if __name__ == "__main__":

    main()
def main():
    print((list(set(["ABC", "ARC"]) - {eval(input())})[0]))


if __name__ == "__main__":
    main()

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


if __name__ == "__main__":
    main()

-    print((list(set(["ABC", "ARC"]) - {eval(input())})[0])) +    s = eval(input()) +    if s == "ABC": +        print("ARC") +    else: +        print("ABC")