function Main(input){
	var S = input.trim();
  	var W_MAX = 3;
  	var b = true;
  	if(S[0] === S[1] && S[0] === S[2])b=false;
  	var result = b?"Yes":"No";
  	console.log(result);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));