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) {
        // Return the minimum number of characters to make the password strong
		String []numbers = {"0","1","2","3","4","5","6","7","8","9"};
				String []lower_case = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
				String []upper_case = {"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"};
				String [] special_characters = {"!","@","#","$","%","^","&","*","(",")","-","+"};
		
				boolean hasLowerCase = stringContainsItemFromList(password, lower_case);
				boolean hasUpperCase = stringContainsItemFromList(password, upper_case);
				boolean hasNumber = stringContainsItemFromList(password, numbers);
				boolean hasSpecial = stringContainsItemFromList(password, special_characters);
				
				
				if(n>=6){
					//length is okay
					if(hasLowerCase&&hasNumber&&hasSpecial&&hasUpperCase){
						return 0;
					}
					else if(!hasLowerCase&&hasNumber&&hasSpecial&&hasUpperCase){
						return 1;
					}
					else if(hasLowerCase&&!hasNumber&&hasSpecial&&hasUpperCase){
						return 1;
					}
					else if(hasLowerCase&&hasNumber&&!hasSpecial&&hasUpperCase){
						return 1;
					}
					else if(hasLowerCase&&hasNumber&&hasSpecial&&!hasUpperCase){
						return 1;
					}
					else if(!hasLowerCase&&!hasNumber&&hasSpecial&&hasUpperCase){
						return 2;
					}
					else if(hasLowerCase&&!hasNumber&&!hasSpecial&&hasUpperCase){
						return 2;
					}
					else if(hasLowerCase&&hasNumber&&!hasSpecial&&!hasUpperCase){
						return 2;
					}
					else if(!hasLowerCase&&hasNumber&&!hasSpecial&&hasUpperCase){
						return 2;
					}
					else if(hasLowerCase&&!hasNumber&&hasSpecial&&!hasUpperCase){
						return 2;
					}
					else if(!hasLowerCase&&!hasNumber&&!hasSpecial&&hasUpperCase){
						return 3;
					}
					else if(hasLowerCase&&!hasNumber&&!hasSpecial&&!hasUpperCase){
						return 3;
					}
					else if(!hasLowerCase&&!hasNumber&&hasSpecial&&!hasUpperCase){
						return 3;
					}
					else if(!hasLowerCase&&!hasNumber&&!hasSpecial&&!hasUpperCase){
						return 4;
					}
				}
				
				
				
				
				else if(n<6){
					//length is short
					
					return 6-n;
					
				}
				
				
				
    }
	
	public static boolean stringContainsItemFromList(String inputStr, String[] items)
	{
	    for(int i =0; i < items.length; i++)
	    {
	        if(inputStr.contains(items[i]))
	        {
	            return true;
	        }
	    }
	    return false;
	}

    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();
    }
}