let rec make_list m n = if m = n then [m] else m :: make_list (m+1) n
let () =
    let x, y, z = Scanf.scanf "%d %d %d\n" (fun x y z -> x, y, z) in
    let lst = List.filter (fun n -> n <> x && n <> y) (make_list 1 z) in
    Printf.printf "%d\n" (List.length lst)