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) {
        // Return the minimum number of characters to make the password strong
        int fl=0,fu=0,fd=0,fs=0;
        char[] a = new char[]{'!','@','#','$','%','^','&','*','(',')','-','+'};
        for(int i=0;i<n;i++)
        {
            if(password.charAt(i)<='z'&&password.charAt(i)>='a')
                fl=1;
            else if(password.charAt(i)<='Z'&&password.charAt(i)>='A')
                fu=1;
            else if(password.charAt(i)<='9'&&password.charAt(i)>='0')
                fd=1;
            else
            {
            for(int k=0;k<12;k++)
                if(password.charAt(i)==a[k])
                    fs=1;
            }
        }
         int t=0;
        if(fl!=1)
            t++;
        if(fu!=1)
            t++;
        if(fd!=1)
            t++;
        if(fs!=1)
            t++;
        if(t+n<6)
            return 6-n;
        else return t;
    }

    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();
    }
}