let s = read_line () in
let check s =
    let n = String.length s in
    let rec loop i =
        if i = n then true else
            if i mod 2 = 0 then (
                if s.[i] >= 'a' && s.[i] <= 'z' then loop (i + 1) else false
            ) else (
                if s.[i] = ' ' then loop (i + 1) else false
            )
    in
    loop 0
in
print_endline @@ if check s then "Yes" else "No"