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;

#define MOD (long long)(1e9+7)
#define REP(i,n) for(ll i = 0; i < n; i++)
#define REP1(i,n) for(ll i = 1; i <= n; i++)

ll gcd(ll a, ll b)
{
  if(b == 0) return a;
  return gcd(b, a % b);
}

int main(void)
{
  string s; cin >> s;
  string ans;
  ans = s;
  if(s[1]=='B') {
    ans[1] = 'R';
  } else {
    ans[1] = 'B';
  }
  cout << ans << endl;
  // cout << (ok?"Yes":"No") << endl;
}