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)

#ifdef DEBUG

#else

#    pragma GCC optimize("O3,no-stack-protector")
#    pragma GCC optimize("unroll-loops")

#    if __cplusplus >= 201703L
#        pragma GCC target("avx2")
#    else
#        pragma GCC target("avx")
#    endif

#endif
// 実数の場合
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define dump(x) cout << x << endl
typedef int64_t Int;
typedef long double Ld;

using namespace std;
using Graph = vector<vector<Int>>;

const double pi = M_PI;
const Int MOD = 1000000007;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    string s;
    cin >> s;

    if (s == "ABC") {
        cout << "ARC" << endl;
    } else {
        cout << "ABC" << endl;
    }

    return 0;
}