#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#define BUFSIZE 1000000
long long A,B,N;
char hoge[BUFSIZE]={0};






int main(void){

    scanf("%s",hoge);

    if(hoge[1]=='B') printf("ARC");
    else printf("ABC");
}
