#include<iostream>
#include<cstring>
#include<algorithm>
#include<set>
using namespace std;
int main(){
	string s;cin>>s;
	set<char>s1;
	for(int i=0;i<3;i++){
		s1.insert(s[i]);
	}
	if(s1.size()==2){
		if(s[0]==s[1])
		cout<<"Yes";
		else cout<<"No";
	}
	else cout<<"No";
}