#include <iostream>
#include <string>

void solve() {
    std::string s;
    std::getline(std::cin, s);

    for (int i = 0; i < (int)s.length(); ++i) {
        if ((s[i] == ' ') != (i % 2 == 1)) {
            std::cout << "No" << std::endl;
            return;
        }
    }

    std::cout << "Yes" << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}