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 Java (OpenJDK 1.8.0) (judge verdict: Runtime Error)

import java.util.*;

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        Integer d[] = new Integer[k];
        Set<Integer> num = new HashSet<>();

        for( int i=0; i<k; i++ ){
            d[i] = sc.nextInt();
            Integer a[][] = new Integer[k][d[i]];

            for( int j=0; j<d[i]; j++ ){
                 a[i][j] = sc.nextInt();
                 num.add(a[i][j]);
            }
        }

        System.out.println( n-num.size() );

    }
}