package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanLines)
	sc.Scan()
	s := sc.Text()
	// fmt.Println(s)
	ok := true
	for i := 0; i < len(s); i++ {
		if (i%2 == 0 && (s[i] < 'a' || s[i] > 'z')) || (i%2 == 1 && s[i] != ' ') {
			ok = false
		}
	}
	if ok {
		fmt.Println("Yes")
	} else {
		fmt.Println("No")
	}
}