#include<iostream>
#define rep(i,j,n) for(int i=j;i<n;i++)
using ll = long long; 
using namespace std;
//vector<int> DX={0,1,0,-1,0,1,-1,-1,1};
//vector<int> DY={0,0,1,0,-1,1,1,-1,-1};

int main(){
    string S; cin >> S;
    int i=0;
    if(S[i]!=S[i+1]){
        cout <<"No" << endl;
        return 0;
    }
    i++;
    if(S[i]==S[i+1]){
        cout <<"No" << endl;
        return 0;
    }
    cout << "Yes" << endl;
}