Problem:
Score : 100 points

Problem Statement

AtCoder Inc. holds a contest every Saturday.

There are two types of contests called ABC and ARC, and just one of them is held at a time.

The company holds these two types of contests alternately: an ARC follows an ABC and vice versa.

Given a string S representing the type of the contest held last week, print the string representing the type of the contest held this week.

Constraints

S is ABC or ARC.

Input

Input is given from Standard Input in the following format:

S

Output

Print the string representing the type of the contest held this week.

Sample Input 1

ABC

Sample Output 1

ARC

They held an ABC last week, so they will hold an ARC this week.

Solution in Python (3.8.2) (judge verdict: Accepted)

import sys
import numpy as np
from math import ceil as C, floor as F, sqrt
from collections import defaultdict as D, Counter as CNT
from functools import reduce as R
 
ALP = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
alp = 'abcdefghijklmnopqrstuvwxyz'
def _X(): return sys.stdin.readline().rstrip().split(' ')
def _S(ss): return tuple(ss) if len(ss) > 1 else ss[0]
def S(): return _S(_X())
def Ss(): return list(S())
def _I(ss): return tuple([int(s) for s in ss]) if isinstance(ss, tuple) else int(ss)
def I(): return _I(S())
def _Is(ss): return list(ss) if isinstance(ss, tuple) else [ss]
def Is(): return _Is(I())

n = S()
print('ABC' if n == 'ARC' else 'ARC')