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

int main() {
	string S;
	getline(cin, S);
	for (int i = 0; i < S.size(); i++) {
		if (i % 2 == 0) {
			if (S[i] == ' ') {
				cout << "No" << endl;
				return 0;
			}
		}
		else {
			if (S[i] != ' ') {
				cout << "No" << endl;
				return 0;
			}
		}
	}
	cout << "Yes" << endl;
}