(* Enter your code here. Read input from STDIN. Print output to STDOUT *)

let sum_bool_list l =
    let rec aux l accu = match l with
        [] -> accu
        |t::q when t -> aux q accu
        |t::q -> aux q (accu+1)
    in aux l 0

let include_number s n =
    let nb = "0123456789" in
    let bol = ref false in
    for i = 0 to 9 do
        for j = 0 to (n-1) do
            if String.get nb i = String.get s j then bol := true
        done
    done;
    !bol
    
let include_lowercase s n =
    let lower_case = "abcdefghijklmnopqrstuvwxyz" in
    let bol = ref false in
    for i = 0 to 25 do
        for j = 0 to (n-1) do
            if String.get lower_case i = String.get s j then bol := true
        done
    done;
    !bol

let include_uppercase s n =
    let upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" in
    let bol = ref false in
    for i = 0 to 25 do
        for j = 0 to (n-1) do
            if String.get upper_case i = String.get s j then bol := true
        done
    done;
    !bol

let include_specchar s n =
    let special_characters = "!@#$%^&*()-+" in
    let bol = ref false in
    for i = 0 to 11 do
        for j = 0 to (n-1) do
            if String.get special_characters i = String.get s j then bol := true
        done
    done;
    !bol

let _ =
    let n = read_int () in
    let s = read_line () in
    let x = (sum_bool_list [include_number s n ; include_lowercase s n ; include_uppercase s n ; include_specchar s n]) in
    Printf.printf "%d" (max x (6-n))