#include "bits/stdc++.h"

using namespace std;

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    string s;
    getline(cin, s);
    for (size_t i = 0; i < s.length(); i += 2) {
        if ('a' <= s[i] && s[i] <= 'z') {
            continue;
        } else {
            cout << "No" << "\n";
            return 0;
        }
    }
    for (size_t i = 1; i < s.length(); i += 2) {
        if (s[i] != ' ') {
            cout << "No" << "\n";
            return 0;
        }
    }
    cout << "Yes" << "\n";
    return 0;
}