import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        char[] arr = sc.nextLine().toCharArray();
        for (int i = 0; i < arr.length; i++) {
            if ((i % 2 == 0 && (arr[i] < 'a' || arr[i] > 'z')) || (i % 2 == 1 && arr[i] != ' ') ) {
                System.out.println("No");
                return;
            }
        }
    System.out.println("Yes");
    }
}