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) {
        
        boolean digit = false;
        boolean lower = false;
        boolean upper = false;
        boolean special = false;
        boolean foundAll = false; 
        
        
        int i = 0;
        
        while (!foundAll && i < n) {
            char ch = password.charAt(i);
            if (0 <= ch - '0' && ch - '0' <= 9) {
                digit = true;
            } else if (0 <= ch - 'a' && ch - 'a' <= 26) {
                lower = true;
            } else if (0 <= ch - 'A'  && ch - 'A' <= 26) {
                upper = true;
            } else if (ch == 33 || (35 <= ch && ch <= 38) ||(40 <= ch && ch <= 43) || ch == 45 || ch == 64 || ch == 94) {
                special = true;
            }
            i++;
            foundAll = digit && lower && upper && special;
        }
        
        int found = 0;
        if (digit) {
            found++;
        //System.out.println(" digit found ");
        }
        if (lower) {
            found++;
        //System.out.println(" lower found ");
        }
        if (upper) {
            found++;
        //System.out.println(" upper found");
        }
        if (special) {found++;
                    // System.out.println(" special found");
                     }
        //System.out.println(" found: " + found);
                     
        
        int change = 0;
        if (n < 6) {change += 6-n;}
        
        
        return Math.max(change, 4-found);
        
        
        
        
    }

    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();
    }
}