#include <stdio.h>

int main() {
  char str;
  
  char a[] = "ABC";
  char b[] = "ARC";
  scanf("%s", &str);
  
  if(str == "ABC") {
    printf("%s\n", b);
  } else if(str == "ARC") {
    printf("%s\n", a);
  } else {
    return ;
  }
  return 0;
}
