#include<iostream>
#include<string>
#include<cassert>
using namespace std;
int main(){
	string S;
	cin>>S;
	assert(S.size()==3&&
	'A'<=S[0]<='Z'&&
	'A'<=S[1]<='Z'&&
	'A'<=S[2]<='Z');
	if(S[0]==S[1]&&S[1]!=S[2]){
		cout<<"Yes"<<endl;
	}else{
		cout<<"No"<<endl;
	}
}