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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef int64_t i6;

#define rep(i, n) for (ll i = 0; i < n; ++i)
#define rep2(i, n) for (ll i = 1; i <= n; ++i)
#define ALL(v) (v).begin(), (v).end()
#define Sort(x) sort(ALL(x))
#define Sort_rev(x) Sort(x);reverse(ALL(x))

template<typename V,typename T>
T find_num(V v, T num) {
    if ( find(ALL(v), num) == v.end() ) {
        return false;
    } else {
        return true;
    }
}

// π M_PI
// deg = rad*180/M_PI

int main() {
    string s;
    cin >> s;
    if ( s == "ABC" ) {
        cout << "ARC" << endl;
    } else {
        cout << "ABC" << endl;
    }
    return 0;
}