#include <stdio.h>
#include <string.h>
int main()
{
    int i,r1,r2;
    char s[100],s1[]="ABC",s2[]="ARC";
    scanf("%s", s);
    r1=strcmp(s,s1);
    r2=strcmp(s,s2);
    if(r1==0)
    {
        printf("ARC\n");
    }
    else if(r2==0)
    {
        printf("ABC\n");
    }
    return 0;
}
