let n = stdin.ReadLine() |> int
let s = stdin.ReadLine()

let f num x = if (num + x) > 90 then ((num + x) - 26) else (num + x)

let len = s.Length

let ls = [for i in 1..len do yield (s.[i - 1] |> int |> f n |> char |> string)]

let g (a:string) b = a + b

List.fold g "" ls
|> stdout.WriteLine