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 u=0,l=0,d=0,s=0;
        for(int i=0;i<password.length();i++){
               if(password.charAt(i)>=65&&password.charAt(i)<=90)
                    u=1;
               else if(password.charAt(i)>=97&&password.charAt(i)<=122)
                    l=1;
               else if(password.charAt(i)>='0'&&password.charAt(i)<='9')
                   d=1;
              else{
                  switch(password.charAt(i)){
                      case '!':
                      case '#':
                      case '$':
                      case '%':
                      case '^':
                      case '&':
                      case '*':
                      case '(':
                      case ')': 
                      case '-':
                      case '+':s=1;
                  }
              }
          }
       int ct=4-(u+l+d+s);
       if(password.length()+ct<6)
           return 6-password.length();
       return ct;
    }
  
    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();
    }
}