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 C# (Mono-mcs 6.8.0.105) (judge verdict: Accepted)

using System;

public class Hello
{
    public static void Main()
    {
        var s = Console.ReadLine().Trim();
        Console.WriteLine(s[1] == 'R' ? "ABC" : "ARC");
    }
}