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++ (Clang 10.0.0) (judge verdict: Accepted)

//~ while (clock()<=69*CLOCKS_PER_SEC)
//~ #pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("O3")
#pragma GCC optimize("-Ofast","-funroll-all-loops","-ffast-math")
//~ #pragma GCC target ("avx2")
//~ #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <algorithm>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <vector>
#include <random>
#include <cmath>
#include <chrono>
#include <cstring>
#include <string>
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cassert>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
//using namespace __gnu_pbds;
using namespace std;
using LL = long long;
#define eps 1e-8
#define fi first
#define se second
#define eb emplace_back
#define SZ(a) int(a.size())
#define ALL(x) (x).begin(),(x).end()
#define trav(a,x) for (auto& a: x)
#define LOG(FMT...) fprintf(stderr, FMT)
#define close std::ios::sync_with_stdio(false),cin.tie(nullptr),cout.tie(nullptr)
#define FOR(i, x, y) for (LL i = (x), _##i = (y); i < _##i; ++i)
#define FORD(i, x, y) for (LL i = (x), _##i = (y); i > _##i; --i)
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#define CASET int ___T; cin>>___T; for(int __CS=1;__CS<=___T;__CS++)
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef pair<int,int> pii;
mt19937 dlsrand(random_device{}());
mt19937 mrand(std::chrono::system_clock::now().time_since_epoch().count()); 
int rnd(int x) { return mrand() % x;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
LL bin(LL x, LL n, LL MOD) {LL ret = MOD != 1;for (x %= MOD; n; n >>= 1, x = x * x % MOD)if (n & 1) ret = ret * x % MOD;return ret;}
inline LL get_inv(LL x, LL p) { return bin(x, p - 2, p); }
const double PI = acos(-1.0);
constexpr int maxn = 1e6+10;
constexpr int mod = 1e9+7;
constexpr int INF = 0x3f3f3f3f;
constexpr ll linf = 0x3f3f3f3f3f3f3f3f;
constexpr ull base=2333, P_1=19260811, P_2=999998639;
void add(int &a,int b) {a+=b; if(a>=mod) a-=mod;}
void dec(int &a,int b) {a-=b; if(a<0) a+=mod;}
int main()
{
    string s;
    cin >> s;
    cout << (s=="ABC"?"ARC":"ABC");

    
}