#include <bits/stdc++.h>
using namespace std;

int main() {
    string s;
    getline(cin, s);
    bool ans = true;
    for (int i = 0; i < s.size(); i++) {
        if (i&1) ans &= (s[i] == ' ');
        else ans &= ('a' <= s[i] and s[i] <= 'z');
    }
    cout << (ans ? "Yes" : "No") << '\n';
    return 0;
}