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 a,e,c,d,f,sum;
        a=0;c=0;d=0;f=0;e=0;
        sum=0;
        
        if(n<6)
           f = 6-n; 
        for(int i=0;i<password.length();i++)
        {
            char b = password.charAt(i);
            if(b>=65&&b<=90)
                a++;
            if(b>=97&&b<=122)
                e++;
            if(b>=48&&b<=57)
                c++;
            if("!@#$%^&*()-+".indexOf(b)>=0)
                d++;
        }
        if(a==0)
            sum++;
        if(e==0)
            sum++;
        if(c==0)
            sum++;
        if(d==0)
            sum++;
        if(sum>f)
            return sum;
        else return f;
        
            
    }

    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();
    }
}