#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <stack>
#include <algorithm>
#include <string>
#include <map>
#include <iterator>
#include <set>
#include <queue>
#include <bitset>
#include <cassert>

using namespace std;


int main() {

    string S;
    getline(cin, S);
    bool ok = true;

    for (int i = 0; i < S.size(); ++i) {
        if (i % 2 == 1) {
            if (S[i] != ' ') {
                ok = false;
                break;
            }
        } else {
            if (!islower(S[i])) {
                ok = false;
                break;
            }
        }
    }

    string res = ok ? "Yes" : "No";

    cout << res << endl;
    return 0;
}