use std::io;
fn main() {
    let mut b:bool = true;
    let mut s: String = String::new();
    io::stdin().read_line(&mut s).expect("Failed to read line");
    let mut s = s.split("");
    let mut s:Vec<&str> = s.collect();
    s.remove(0);
    s.remove(s.len()-1);
    s.remove(s.len()-2);
    for i in 0..s.len()
    {
        if((i + 1) % 2 == 0 && s.len()-1 != i)
        {
            if(s[i] != " ")
            {
                b = false;
                break;
            }
        }
        else
        {
            if(s[i] == " ")
            {
                b = false;
                break;
            }
        }
    }
    if(b == true){ print!("Yes"); }
    else { print!("No"); }
}