#include <bits/stdc++.h>
using namespace std;
using namespace chrono;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
#endif

int main() {
    string s;
    getline(cin, s);

    bool flag = true;
    for (int64_t i = 0; i < s.size(); i++) {
        if (i % 2 == 0) {
            flag &= 'a' <= s[i] && s[i] <= 'z';
        } else {
            flag &= s[i] == ' ';
        }
    }

    cout << (flag ? "Yes" : "No") << endl;

    return 0;
}