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>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#define db(x) (cerr << #x << ": " << (x) << '\n')
#define cps CLOCKS_PER_SEC
#define tests(t) int t; cin >> t; while(t--)
#define iceil(n, x) (((n) + (x) - 1) / (x))
#define eb emplace_back
#define pb push_back
#define pf push_front
#define pob pop_back
#define pof pop_front
#define sz size()
#define all(v) (v).begin(), (v).end()
#define uni(v) sort(all(v)), (v).erase(unique(all(v)), (v).end())
#define fi first
#define se second
#define bitcount(x) __builtin_popcount(x)
#define bit(x) (1LL << x)
#define PI acos(-1.0)
#define EPS 1e-9

#define mod 1000000007
#define maxn 200015

using namespace std;

using namespace __gnu_pbds;
template<class key, class cmp = std::less<key>>
using ordered_set = tree<key, null_type, cmp, rb_tree_tag, tree_order_statistics_node_update>;
///All indexing is 0-based
///methods: find_by_order(k); & order_of_key(k);
///To make it an ordered_multiset, use pairs of (value, time_of_insertion)
///to distinguish values which are similar

typedef long long ll;
typedef double ld;
typedef pair<ll, ll> par;


char s[14];

int main()
{
    #ifdef acm
    freopen("a.in","r",stdin);
    #endif // acm
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> s;

    if(s[1] == 'B')
        cout << "ARC\n";
    else
        cout << "ABC\n";






}