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 dig=0,sc=0,uc=0,sp=0,x=0;
        for(int i=0;i<n;i++){
            char ch=password.charAt(i);
            if((int)ch>47 && (int)ch<58 && dig==0) dig++;
            if((int)ch>64 && (int)ch<91 && uc==0) uc++;
            if((int)ch>96 && (int)ch<123 && sc==0) sc++;
            if(((int)ch>32 && (int)ch<46 || (int)ch==64 || (int)ch==94) && sp==0 && (int)ch!=34 && (int)ch!=39 && (int)ch!=44) sp++;
        }
        if(dig==0) x++;
        if(uc==0) x++;
        if(sc==0) x++;
        if(sp==0) x++;
        if(x+n>=6)
        return x;
        else return 6-n;
    }

    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();
    }
}