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 PHP (7.4.4) (judge verdict: Wrong Answer)

<?php
$line = fgets(STDIN);

// STDIN(スタンダードインプット:標準入力)から1行を取得

if($line == "ABC"){
    $next = "ARC";
}else{
    $next = "ABC";
}
echo $next; // 結果：1 2 3