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) {
         long cap = 0;
         long small = 0;
         long num = 0;
         long spe = 0;
         int finalRes = 0;
        for(int i=0;i<n;i++){
            if(password.charAt(i)>=97 && password.charAt(i)<=122)
                small++;
            else if(password.charAt(i)>=48 && password.charAt(i)<=57)
                num++;
            else if (password.charAt(i)>=65 && password.charAt(i)<=90)
                cap++;
            else
                spe++;
        }
        
        int len = 0;
        if(password.length()>=6){
            if(cap<1)
                finalRes++;
            if(small<1)
                finalRes++;
            if(num<1)
                finalRes++;
            if(spe<1)
                finalRes++;
            
            return finalRes;
        }else{
            if(cap<1)
                len++;
            if(small<1)
                len++;
            if(num<1)
                len++;
            if(spe<1)
                len++;
            
            if(len+password.length()<6)
                len +=(6-len-password.length());

            return len;
        }
    }

    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();
    }
}