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

#define max 5

int main()
{
    char S[max];
    gets(S);

    if(strcmp(S,"ABC")==0)
    {
        printf("ARC");
    }
    else if(strcmp(S,"ARC")==0)
    {
        printf("ABC");
    }

    return  0;
}
