let ``No.756 チャンパーノウン定数 (1)``() =

  let rec loop n i =
    let len = (string n).Length
    match i with
    | 1 -> match len with
          | 1 -> n
          | 2 -> n / 10
          | _ -> 1
    | 2 -> match len with
          | 1 -> loop (n+1) (i-len)
          | 2 -> n % 10
          | _ -> 0
    | 3 ->  if n = 100 
            then 0
            else loop (n+1) (i-len)
    | _ -> 
           loop (n+1) (i-  len )

  stdin.ReadLine()|>int
  |> loop 1
  |> stdout.WriteLine

  ()
``No.756 チャンパーノウン定数 (1)``()