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 p) {
        // Return the minimum number of characters to make the password strong
        int l=p.length();
        int cnt=0;
        boolean flg1=false,flg2=false,flg3=false,flg4=false;
        for(int i=0;i<l;i++){
            char c=p.charAt(i);
            if((c=='0'||c=='1'||c=='2'||c=='3'||c=='4'||c=='5'||c=='6'||c=='7'||c=='8'||c=='9')&&!flg1){
                flg1=true;cnt++;}
            if((c>=65&&c<=90)&&!flg2){
                flg2=true;cnt++;}
            if((c>=97&&c<=122)&&!flg3){
                flg3=true;cnt++;}
            if((c=='!'||c=='@'||c=='#'||c=='$'||c=='%'||c=='^'||c=='&'||c=='*'||c=='('||c==')'||c=='-'||c=='+')&&!flg4){
                flg4=true;cnt++;}
        }
       // System.out.println(cnt);
        if(6-l<0)        
            return (4-cnt);
        else
            if(6-l>4-cnt)
                return 6-l;
            else
                return (4-cnt);
    }

    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();
    }
}