use std::io::*;
use std::str::FromStr;
use std::cmp::{min, max};

fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char) 
        .skip_while(|c| *c == '\n')
        .take_while(|c| *c != '\n')
        .collect();
    token.parse().ok().expect("failed to parse token")
}

fn main() {
    let s: Vec<char> = read::<String>().chars().collect();
    let l = s.len();
    for i in 0..l {
        if i % 2 == 0 && !('a' <= s[i] && s[i] <= 'z') {
            println!("No");
            return;
        } else if i % 2 == 1 && s[i] != ' ' {
            println!("No");
            return;
        }
    }
    println!("Yes");
}