function main(arg) {
  if (arg == "ABC") {
    console.log("ARC");
    return;
  } else if (arg == "ARC") {
    console.log("ABC");
    return;
  }
}
// main(require("fs").readFileSync("/dev/stdin", "utf8"));
main("ABC");
//https:/ / atcoder.jp / contests / abc166 / tasks / abc166_a;
