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
        char[] ch=password.toCharArray();
        int a=0;
        int b=0;
        int c=0;
        int d=0;
        for (int i=0;i<n;i++){
            if (ch[i]>=65 && ch[i]<=90){
                a=1;
            }
            if (ch[i]>=97 && ch[i]<=122){
                b=1;
            }
            if (ch[i]>=48 && ch[i]<=57){
                c=1;
            }
            if ((ch[i]>=35 && ch[i]<=38)||(ch[i]>=40 && ch[i]<=43)||(ch[i]=='@')||(ch[i]=='!')||(ch[i]=='^')||(ch[i]=='-')){
                d=1;
            }
            
        }
        int res=0;
        if (a==0)
            res++;
        if (b==0)
            res++;
        if (c==0)
            res++;
        if (d==0)
            res++;
        if (n>=6)
            return res;
        else {
            return ((6-n)>res?(6-n):res);
        }
    }

    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();
    }
}