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 min = 0,min1=0;
        if(n<6)
            min = 6-n;
            
       int arr[] = new int[4];
        for(int i=0;i<n;i++){
           char ch = password.charAt(i);
            if(Character.isUpperCase(ch)==true)
                arr[2]++;
            else if(Character.isLowerCase(ch)==true)
                arr[1]++;
            else if(ch == '!'||ch == '@'||ch == '#'||ch == '$'||ch == '%'||ch == '^'||ch == '&'||ch == '*'||ch == '*'||ch == '('||ch == ')'||ch == '-'||ch == '+')
                arr[3]++;
            else if(ch>=48&&ch<=57)
                arr[0]++;
       }
        // Return the minimum number of characters to make the password strong
        for(int i=0;i<4;i++){
            if(arr[i]==0)
                min1++;
        }
        return min>min1?min:min1;
    }

    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();
    }
}