open Str
let lst = split_delim (regexp " ") (read_line ())
let rec make_nlst n = if n = 0 then [] else (n-1) :: make_nlst (n-1)
let abc = split (regexp "") "abcdefghijklmnopqrstuvwxyz"
let f x = x mod 2 = 1 && List.nth lst x = "" || x mod 2 = 0 && List.mem (List.nth lst x) abc 
let ans = List.for_all (fun i -> f i) (make_nlst (List.length lst))
let () = print_endline (if ans then "Yes" else "No")