import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
  static int MAX = 4;
        
    static int minimumNumber(int n, String password) {
        int found =0;
        boolean number = false;    
        boolean lower = false;
        boolean upper = false;
        boolean special = false;
        for(char c : password.toCharArray()) {
                int a = c;
            if(found == 4 ){
                break;
            }
            if(!number) {
                if(a >= 48 && a <= 57) {
                    number = true;
                    ++found;
                    continue;
                }
            }
            if(!lower) {
                if(a >= 97 && a <= 122) {
                    lower = true;
                    ++found;
                    continue;
                }
            }
             if(!upper) {
                if(a >= 65 && a <= 90) {
                    upper = true;
                    ++found;
                    continue;
                }
            }
            if(!special) {
             if(a == 33 || a ==45 || a == 64 ||(a >= 35 && a <=38) || a == 94 || (a >=40 && a <=43)) {
                    special = true;
                    ++found;
                }
            }
        } 
        int diff = 0;
        if(password.length() <6){
            diff = 6 - password.length();
        }
            return Math.max(MAX - found,diff);
    }

    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();
    }
}