import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
    String s = sc.nextLine();

		int i = 0;
    for ( ; i < s.length(); i++) {
    	String c = String.valueOf(s.charAt(i));
      if (i % 2 == 0) {
      	if (c.equals(" ")) {
					break;
				}
      }
			if (i % 2 == 1) {
				if (!(c.equals(" "))) {
					break;
				}
			}
    }

		if (i == s.length()) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	}
}