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 numbers = 0;
        int lCase = 0;
        int uCase = 0;
        int sCase = 0;
        int len = password.length();
        for (int i = 0; i < len; i++) {
            int ascii = (int)password.charAt(i);
            if (ascii >= 65 && ascii <= 90) {
                uCase++;
            } else if (ascii >= 97 && ascii <= 122) {
                lCase++;
            } else if (ascii >= 48 && ascii <= 57) {
                numbers++;
            } else {
                sCase++;
            }
        }
        int count = 0;
        if (lCase == 0) {
            count++;
        } 
        if (uCase == 0) {
            count++;
        }
        if (numbers == 0) {
            count++;
        }
        if (sCase == 0) {
            count++;
        }
        if (len + count < 6) {
            count += 6 - len - count;
        }
        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();
    }
}