import java.util.Scanner;

public class q1 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String s = sc.next();

		int output=0;
		
		String numbers = "0123456789";
		String lower_case = "abcdefghijklmnopqrstuvwxyz";
		String upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
		String special_characters = "!@#$%^&*()-+";
		
		boolean flag1=false;
		boolean flag2=false;
		boolean flag3=false;
		boolean flag4=false;

		//System.out.println(s);
		
		for (int i = 0; i < numbers.length(); i++) {
			if(s.contains(""+numbers.charAt(i)))
				{
				//System.out.println(numbers.charAt(i));
				flag1=true;
				break;
				}
		}
		
		for (int i = 0; i < lower_case.length(); i++) {
			if(s.contains(""+lower_case.charAt(i)))
				{
				flag2=true;
				break;
				}
		}
		
		for (int i = 0; i < upper_case.length(); i++) {
			if(s.contains(""+upper_case.charAt(i)))
				{
				flag3=true;
				break;
				}
		}
		
		for (int i = 0; i < special_characters.length(); i++) {
			if(s.contains(""+special_characters.charAt(i)))
				{
				flag4=true;
				break;
				}
		}
		if(!flag1)
			output++;
		
		if(!flag2)
			output++;
		
		if(!flag3)
			output++;
		
		if(!flag4)
			output++;
		
		//System.out.println(output);
		
		if(s.length()+output<6)
			output=6-s.length();
		
		System.out.println(output);
	}

}