open Batteries
let cut st str = String.init (String.length str - st) (fun a -> String.get str (a+st))
let get num str = String.init num (fun a -> String.get str a)
let s = read_line ()
let n = String.length s
let n_1 = get ((n-1)/2) s
let n_2 = cut ((n+3)/2-1) s
let half_n1 = get ((String.length n_1)/2) n_1
let end_n1 = cut ((String.length n_1)/2+1) n_1
let half_n2 = get ((String.length n_2)/2) n_2
let end_n2 = cut ((String.length n_2)/2+1) n_2

let _ = (if half_n1 = end_n1 && half_n2 = end_n2 && n_1 = n_2 then "Yes" else "No") |> print_endline