(*
ocamlfind ocamlopt -package batteries -linkpkg main.ml -o a.out
*)
open Batteries

let n = Scanf.sscanf (read_line ()) "%d" ( fun n -> n)
let nn = n + ((n - 1) / 26)

let filter n = 
        if n = 1 then
                "a"
        else
        if n = 2 then
                "b"
        else
        if n = 3 then
                "c"
        else
        if n = 4 then
                "d"
        else
        if n = 5 then
                "e"
        else
        if n = 6 then
                "f"
        else
        if n = 7 then
                "g"
        else
        if n = 8 then
                "h"
        else
        if n = 9 then
                "i"
        else
        if n = 10 then
                "j"
        else
        if n = 11 then
                "k"
        else
        if n = 12 then
                "l"
        else
        if n = 13 then
                "m"
        else
        if n = 14 then
                "n"
        else
        if n = 15 then
                "o"
        else
        if n = 16 then
                "p"
        else
        if n = 17 then
                "q"
        else
        if n = 18 then
                "r"
        else
        if n = 19 then
                "s"
        else
        if n = 20 then
                "t"
        else
        if n = 21 then
                "u"
        else
        if n = 22 then
                "v"
        else
        if n = 23 then
                "w"
        else
        if n = 24 then
                "x"
        else
        if n = 25 then
                "y"
        else
                "z"
let rec f n =
        if n = 0 then
                []
        else
                (n mod 26) :: (f (n / 26))


let ans = 
        List.rev (f n)
        |> List.map filter

let () =
        List.iter (fun elmnt ->
                Printf.printf "%s" elmnt
        ) ans
