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 str) {
    	char c[] = new char[str.length()];
    	int len = str.length();
    	c = str.toCharArray();
    	int count = 0;
    	for(char ch:c){
    		int ascii = (int) ch;
    		if(ascii>=65 && ascii<=90){
    			count++;
    			break;
    		}
    		
    	}
    	for(char ch:c){
    		int ascii = (int) ch;
    		if(ascii>=48 && ascii<=57){
    			count++;
    			break;
    		}
    		
    	}
    	for(char ch:c){
    		int ascii = (int) ch;
    		if(ascii>=97 && ascii<=122){
    			count++;
    			break;
    		}
    		
    	}
    	
    	for(char ch:c){
    		int ascii = (int) ch;
    		if(ascii>=33 && ascii<=45){
    			count++;
    			
    			break;
    		}
    		
    	}
    	if(len>=6){
            if(count == 0){
                return 0;
            }
    		return 4 - count;
            
        }
    	else
            if(4-count>6-len){
                return 4 - count;
            }
        else{
    		return 6 - len;
        }
        // Return the minimum number of characters to make the password strong
        
    }

    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();
    }
}