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 s) { int num=0,low=0,high=0,spec=0;
        // Return the minimum number of characters to make the password strong
        for(int i=0;i<n;i++){
            if(s.charAt(i)>='0' && s.charAt(i)<='9')
                 num=1;
            else if(s.charAt(i)>='a' && s.charAt(i)<='z')
                 low=1;
            else if(s.charAt(i)>='A' && s.charAt(i)<='Z')
                 high=1;
            else if(s.charAt(i)=='!' || s.charAt(i)=='@'|| s.charAt(i)=='#'|| s.charAt(i)=='$'|| s.charAt(i)=='%'|| s.charAt(i)=='^'|| s.charAt(i)=='&'|| s.charAt(i)=='*'|| s.charAt(i)=='('|| s.charAt(i)==')'|| s.charAt(i)=='-'|| s.charAt(i)=='+' )
                 spec=1;
        }
          int count=0;
          if(num==1)
              count++;
            if(low==1)
                count++;
           if(high==1)
               count++;
         if(spec==1)
             count++;
                                               int nu=0;
           if(n<6 )
               nu=6-n;
           count=4-count;
           if(nu>count)
               return nu;
            else return count;
              
    }

    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();
    }
}