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

int main(void){
  char a[3];
  char s[3] = "ABC";
  char s1[3] = "ARC";
  scanf("%s", &a);
  if(strcmp(a,s) == 0)
    printf("%s", s1);
  else
    printf("%s", s);
  return 0;
}