import java.util.*;
import java.io.*;
import static java.lang.Math.*;
public class Main
{  
    static MyScanner scan;
    static PrintWriter pw;
    public static void main(String[] args) {
        new Thread(null,null,"_",1<<25)
        {
           public void run()
           {
               try
               {
                   solve();
               }
               catch(Exception e)
               {  
                   e.printStackTrace();
                   System.exit(1);
               }
           }
        }.start();
    }
    static void solve() throws IOException
    {
        scan = new MyScanner();
        pw = new PrintWriter(System.out,true);
        StringBuilder sb = new StringBuilder();
        int n = ni();
        String s = ne();
        boolean number = false;
        boolean lowercase = false;
        boolean uppercase = false;
        boolean special = false;
        HashSet<Character> num = new HashSet();
        HashSet<Character> low = new HashSet();
        HashSet<Character> up = new HashSet();
        HashSet<Character> sp = new HashSet();
        String numbers = "0123456789";
        String lower_case = "abcdefghijklmnopqrstuvwxyz";
        String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String special_characters = "!@#$%^&*()-+";
        for(int i=0;i<numbers.length();++i)
            num.add(numbers.charAt(i));
        for(int i=0;i<lower_case.length();++i)
            low.add(lower_case.charAt(i));
        for(int i=0;i<upper_case.length();++i)
            up.add(upper_case.charAt(i));
        for(int i=0;i<special_characters.length();++i)
            sp.add(special_characters.charAt(i));
        for(int i=0;i<n;++i)
        {
            if(num.contains(s.charAt(i)))
                number = true;
            else if(up.contains(s.charAt(i)))
                uppercase = true;
            else if(low.contains(s.charAt(i)))
                lowercase = true;
            else special = true;
        }
        int cnt = 0;
        if(!number)
            ++cnt;
        if(!uppercase)
            ++cnt;
        if(!lowercase)
            ++cnt;
        if(!special)
            ++cnt;
        pl(max(cnt,6-n));
        pw.flush();
        pw.close();
    }
    static int ni() throws IOException
    {
        return scan.nextInt();
    }
    static long nl() throws IOException
    {
        return scan.nextLong();
    }
    static double nd() throws IOException
    {
        return scan.nextDouble();
    }
    static String ne() throws IOException
    {
        return scan.next();
    }
    static String nel() throws IOException
    {
        return scan.nextLine();
    }
    static void pl()
    {
        pw.println();
    }
    static void p(Object o)
    {
        pw.print(o+" ");
    }
    static void pl(Object o)
    {
        pw.println(o);
    }
    static void psb(StringBuilder sb)
    {
        pw.print(sb);
    }
    static class MyScanner
    {
        BufferedReader br;
        StringTokenizer st;
        MyScanner()
        {
            br = new BufferedReader(new InputStreamReader(System.in));
        }
        String nextLine()throws IOException
        {
            return br.readLine();
        }
        String next() throws IOException
        {
            if(st==null || !st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            return st.nextToken();
        }
        int nextInt() throws IOException
        {
            return Integer.parseInt(next());
        }
        long nextLong() throws IOException
        {
            return Long.parseLong(next());
        }
        double nextDouble() throws IOException
        {
            return Double.parseDouble(next());
        }
    }
}