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# (.NET Core 3.1.201) (judge verdict: Accepted)

using Microsoft.VisualBasic;
using System;
using static System.Console;

namespace ProblemA
{
    class Program
    {
        static void Main(string[] args)
        {
            string s = ReadLine();

            switch(s)
            {
                case "ABC":
                    WriteLine("ARC");
                    break;
                case "ARC":
                    WriteLine("ABC");
                    break;
            }    
        }
    }
}