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) { if (arr[i] < 'a' || arr[i] > 'z') { System.out.println("No"); return; } } else { if (arr[i] != ' ') { System.out.println("No"); return; } } } System.out.println("Yes"); } }