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

public class Solution {

    

    public static void main(String[] args) {
       Scanner sc=new Scanner(System.in);
       long T=sc.nextLong();
       String str=sc.next();
       int len=6;
       int lower=1,upper=1,special=1,digit=1;
       for(int i=0;i<T;i++) {
    	   char a=str.charAt(i);
    	   if(Character.isDigit(a)) {
    		   digit=0;
    	   }else if(Character.isLowerCase(a))
    		   lower=0;
    	   else if(Character.isUpperCase(a)) {
    		   upper=0;
    	   }else {
    		   special=0;
    	   }
       }
       int lenreq=lower+upper+digit+special;
       if(T>=len) {
    	   System.out.println(lenreq);
       }else {
    	   if(len-T>=lenreq) {
    		   System.out.println(len-T);
    	   }else {
    		   System.out.println(lenreq);
    	   }
       }
       
    }
}