import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String s = br.readLine();
		br.close();

		for (int i = 0; i < s.length(); i++) {
			if (i % 2 == 1) {
				if (s.charAt(i) != ' ') {
					System.out.println("No");
					return;
				}
			} else {
				if (s.charAt(i) == ' ') {
					System.out.println("No");
					return;
				}
			}
		}
		System.out.println("Yes");
	}
}