"use strict";

const main = arg => {
    const inputList = arg.trim().split("\n");
  // 回答を記述
  const lastTest = inputList[0]
  if (lastTest == "ABC") {
    console.log("ARC");
  } else {
    console.log("ABC")
  }
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));