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<iostream>
#include<algorithm>
#include<cmath>
#include<vector>
#include<map>
#include<set>
#include<string>

#define fast_io ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);

using namespace std;

//inline int read(){int t = 0;int neg=1;char c;while((c=getchar_unlocked())!='\n'&&c!=' '&&c!=EOF){if(c=='-'){neg=-1;continue;}t=t*10+c-48;}return neg*t;}
//inline int readl(){long long t = 0;long long neg=1ll;char c;while((c=getchar_unlocked())!='\n'&&c!=' '&&c!=EOF){if(c=='-'){neg=-1ll;continue;}t=t*10+c-48;}return neg*t;}

#define debug(x) cout<<(#x)<<"="<<(x)<<", ";
#define debug1(x) debug(x) cout<<'\n';
#define debug2(x1, x2) debug(x1) debug(x2) cout<<'\n';
#define debug3(x1, x2, x3) debug(x1) debug(x2) debug(x3) cout<<'\n';
#define debug4(x1, x2, x3, x4) debug(x1) debug(x2) debug(x3) debug(x4) cout<<'\n';
#define debug5(x1, x2, x3, x4, x5) debug(x1) debug(x2) debug(x3) debug(x4) debug(x5) cout<<'\n';

typedef long long int lli;
typedef unsigned long long int ulli;
typedef pair<int,int> pi;
typedef pair<lli,lli> plli;
typedef vector<int> vi;
typedef vector<lli> vlli;
typedef vector<pi> vpi;
typedef vector<plli> vplli;
const lli M=1000000007ll;

int main(){
	fast_io
	string s; cin>>s;
	if(s[1]=='B') cout<<"ARC";
	else cout<<"ABC"; 
	
	return 0;
}