#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops")
#pragma GCC optimize("no-stack-protector,fast-math")
#define IO ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#include<iostream>
#include<bits/stdc++.h>
using namespace std;
#define ll long long 
#define ld long double
//const int N =2e5+5;

int main()
{
    string s1="ABC",s2="ARC";
    string in="";
    cin>>in;
    (in ==s1)?cout<<s2<<endl:cout<<s1<<endl;
}
