let () =
    let lst = Array.to_list (Array.init 9 (fun i -> Scanf.scanf "%1s" (fun x -> (i, x)))) in 
    let checklst = ["y"; "u"; "k"; "i"; "c"; "o"; "d"; "e"; "r"] in
    let n = List.fold_left (fun a (n, x) -> if x = "?" then n else a) max_int lst in
    Printf.printf "%s\n" (List.nth checklst n)