import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    static int minimumNumber(int n, String password) {
        int res=Math.max(0, 6-n);
        boolean[] ok=new boolean[4];
        for (char ch : password.toCharArray()) {
            if ("0123456789".indexOf(ch) >=0)ok[0]=true;
            else if("abcdefghijklmnopqrstuvwxyz".indexOf(ch) >=0)ok[1]=true;
            else if("ABCDEFGHIJKLMNOPQRSTUVWXYZ".indexOf(ch) >=0)ok[2]=true;
            else if("!@#$%^&*()-+".indexOf(ch) >=0)ok[3]=true;
        }
        int miss=0;
        for (int i=0;i<4;++i)if (!ok[i])++miss;
        return Math.max(res, miss);
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        String password = in.next();
        int answer = minimumNumber(n, password);
        System.out.println(answer);
        in.close();
    }
}