#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
#include<set>
#include<bitset>
#include<math.h>
#include<map>
#include<queue>
#include<iomanip>
using namespace std;

int main(){
    string s;
    cin >> s;
    for (int i = 0; i < s.size(); i++){
        if ((i%2 == 0 && (s[i] < 'a' || s[i] > 'x')) || (i%2 == 1 && s[i] != ' ')){
            cout << "No" << endl;
            return 0;
        }
    }
    cout << "Yes" << endl;
}