#include <stdio.h>
#include<stdlib.h>
#include<string.h>
#include <assert.h>

int main(void) {
    //int a, b, c, d;
    //int ans;
    //scanf("%d", &a);
    //scanf("%d", &b);
    char s[5];
    char a[] = "ABC";
    //char b[] = "ARC";
    scanf("%s", s);



    if (strcmp(s,a) == 0) {
        puts("ARC");
    }
    else {
        puts("ABC");
    }


    return 0;
}
