/**
 *  author:   TakeruOkuyama
 *  created:  2020-04-09 13:18:37
**/
#include <bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (n); i++)
using namespace std;
using ll = long long;
using P = pair<int, int>;

int main(){
    string S;
    cin >> S;
    rep(i, S.size()){
        if(i % 2 == 0){
            if('a' <= S[i] == S[i] <= 'z'){

            }else{
                cout << "No" << endl;
                return 0;
            }
        }else{
            if(S[i] == ' '){

            }else{
                cout << "No" << endl;
                return 0;
            }
        }
    }
    cout << "Yes" << endl;
return 0;}

/**
**/