fn main() {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    let s = s.trim();

    for (i, c) in s.char_indices() {
        if (i & 1 == 0 && !('a'..='z').contains(&c)) || (i & 1 == 1 && c != ' ') {
            println!("No");
            return;
        }
    }

    println!("Yes");
}