import java.util.*;

class Main1{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		boolean flag = true;
		for(int i = 0; i < s.length(); i++){
			if(i%2 == 0){
				if(!(s.charAt(i)>=97&&s.charAt(i)<=122)){
					flag = false;
					break;
				}
			}else{
				if(!(s.substring(i,i+1).equals(" "))){
					flag = false;
					break;
				}
			}
		}
		System.out.println(flag?"Yes":"No");
	}
}