let solve n =
  let rec f n l r =
    if l = 0 && r = 0 then 1
    elif n > 0 then
      if l > 0 then
        (f (n-1) l (r-1)) + (f (n+1) (l-1) r)
      else
        f (n-1) l (r-1)
    else
      f (n+1) (l-1) r
  f 0 n n

let n = stdin.ReadLine() |> int

solve n
|> stdout.WriteLine