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 Rust (1.42.0) (judge verdict: Accepted)

use std::io::*;
use std::str::FromStr;

//portable utility
#[allow(dead_code)]
fn switch<T>(flag: bool, true_value: T, false_value: T) -> T {
    if flag {
        true_value
    } else {
        false_value
    }
}

#[allow(dead_code)]
fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed to parse token")
}

#[allow(dead_code)]
fn read_string() -> Vec<char> {
    read::<String>().chars().collect()
}

#[allow(dead_code)]
fn read_vector<T: FromStr>(number: usize) -> Vec<T> {
    (0..number).map(|_| read()).collect()
}

fn main() {
    let text = read_string();
    if text == vec!['A', 'B', 'C'] {
        println!("ARC");
    } else {
        println!("ABC");
    }
}