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) {
        String numbers = "0123456789";
        String lower_case = "abcdefghijklmnopqrstuvwxyz";
        String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        String special_characters = "!@#$%^&*()-+";
            
        boolean nu=false, l=false, u=false, s=false;
        int miss = 0;
        char[] sArr = password.toCharArray();
        for (int i=0; i<sArr.length; i++){
            if (numbers.indexOf(sArr[i]) != -1){
                nu=true;
                continue;
            } else  if (lower_case.indexOf(sArr[i]) != -1){
                l=true;
                continue;
            } else  if (upper_case.indexOf(sArr[i]) != -1){
                u=true;
                continue;
            } else  if (special_characters.indexOf(sArr[i]) != -1){
                s=true;
                continue;
            } else {
                break;
            }                
        }
        if (nu==false) miss++;
        if (l==false) miss++;
        if (u==false) miss++;
        if (s==false) miss++;
        int reqPassLength = 0;
        if (password.length()<6){
            if ((6-password.length()) > miss){
                return 6-password.length();
            } else {
                return miss;                
            }                
        }
        return miss;
    }

    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();
    }
}