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

int main(void)
{
    char B[4] = "ABC";
    char R[4] = "ARC";
    char S[3];
    scanf_s("%s %s %s", &S[0], &S[1], &S[2]);
    
    if (strcmp(S, R) == 0) {
        printf("%s\n", B);
    }
    else {
        printf("%s\n", R);
    }

    return 0;
}