function Main(input) {
  // input = input.replace(/\n/g, ' ');
  // input = input.split(" ");
  input = input.split("");
  if(input[0]==input[1] && input[1]==input[2]){
    console.log("No");
  }else{
    console.log("Yes");
  }
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));