import java.io.*;
import java.lang.*;
import java.util.*;

class Main{
    public static void main (String[] args) throws IOException{
        String s;
        s=new BufferedReader(new InputStreamReader(System.in)).readLine();
        for(int i=0;i<s.length();i++){
            if(i%2==0&&s.charAt(i)==' '||i%2==1&&s.charAt(i)!=' '){
                System.out.println("No");
                System.exit(0);
            }
        }
                System.out.println("Yes");
    }
}