#include <bits/stdc++.h>

using namespace std;

using ll = long long;

bool solve(string& s) {
    int n = s.size();
    for (int i = 0; i < n; i++) {
        if (i % 2 == 0) {
            if (s[i] == ' ') return false;
        } else {
            if (s[i] != ' ') return false;
        }
    }
    return true;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    string s;
    getline(cin, s);
    cout << (solve(s) ? "Yes" : "No") << "\n";
    return 0;
}