# import numpy as np

# from itertools import permutations

# from itertools import combinations

# from itertools import combinations_with_replacement

# import queue

# import heapq





def main():

    # N, M = map(int, input().split())

    # As = list(map(int, input().split()))



    S = eval(input())



    if S == 'ABC':

        print('ARC')

    else:

        print('ABC')





if __name__ == "__main__":

    main()

def main():

    contest_last_week = eval(input())

    

    abc, arc = ('ABC', 'ARC')

    

    if contest_last_week == abc:

        contest_this_week = arc

    else:

        contest_this_week = abc

        

    print(contest_this_week)





if __name__ == "__main__":

    main()

# import numpy as np
# from itertools import permutations
# from itertools import combinations
# from itertools import combinations_with_replacement
# import queue
# import heapq
def main():
    # N, M = map(int, input().split())
    # As = list(map(int, input().split()))
    S = eval(input())
    if S == "ABC":
        print("ARC")
    else:
        print("ABC")


if __name__ == "__main__":
    main()

def main():
    contest_last_week = eval(input())
    abc, arc = ("ABC", "ARC")
    if contest_last_week == abc:
        contest_this_week = arc
    else:
        contest_this_week = abc
    print(contest_this_week)


if __name__ == "__main__":
    main()

-# import numpy as np -# from itertools import permutations -# from itertools import combinations -# from itertools import combinations_with_replacement -# import queue -# import heapq -    # N, M = map(int, input().split()) -    # As = list(map(int, input().split())) -    S = eval(input()) -    if S == "ABC": -        print("ARC") +    contest_last_week = eval(input()) +    abc, arc = ("ABC", "ARC") +    if contest_last_week == abc: +        contest_this_week = arc -        print("ABC") +        contest_this_week = abc +    print(contest_this_week)