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 count=0;
        //for upper case
            for(int upper_i=65;upper_i<=90;upper_i++)
            {
                for(int i=0;i<n;i++)
                {
                    if(password.charAt(i)==upper_i)
                    {
                        count++;
                        break;
                    }
                }
                if(count>0)
                    break;
            }
        // for lower case
        int temp=count;
        for(int lower_i=97;lower_i<=122;lower_i++)
            {
                for(int i=0;i<n;i++)
                {
                    if(password.charAt(i)==lower_i)
                    {
                        count++;
                        break;
                    }
                }
                if(count>temp)
                    break;
            }
        //for number
        temp=count;
        for(int number_i=48;number_i<=57;number_i++)
            {
                for(int i=0;i<n;i++)
                {
                    if(password.charAt(i)==number_i)
                    {
                        count++;
                        break;
                    }
                }
                if(count>temp)
                    break;
            }
        //for special character
        temp=count;
        String special = "!@#$%^&*()-+";
        for(int j=0;j<12;j++)
            {
                for(int i=0;i<n;i++)
                {
                    if(password.charAt(i)==special.charAt(j))
                    {
                        count++;
                        break;
                    }
                }
                if(count>temp)
                    break;
            }
        int len=password.length();
        if(len>=6 && count>=4)
            return 0;
        else if(len>=6 && count<4)
        {
               return 4-count;
        }
        else if(len<6 && count>=4)
        {
            return 6-len;
        }
        else if(len<6 && count<4)
        {
            if(6-len>=4)
                return 6-len;
            else 
            {
                int x=6-len;
                int y=4-count;
                if(x>y)
                    return x;
                else return y;
            }
        }
       else return 0;
    }

    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();
    }
}