#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < n; ++i)
using namespace std;

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

    return 0;
}