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) {
        char []b=password.toCharArray();
        boolean S=false,U=false,L=false,N=false;
        int req=0;
        if(n<6)
                req=6-n;
        int r=0;
        for(char c:b){
            if((int)c <=57 &&(int)c >=48){
                N=true;
            }
            if(c=='!' ||c=='@' ||c=='#' ||c=='$' ||c=='%' ||c=='^' ||c=='&' ||c=='*' ||c=='(' ||c==')' ||c=='-' ||c=='+')
                S=true;
            if((int)c <=90 &&(int)c >=65){
                U=true;
            }
            if((int)c <=122 &&(int)c >=97){
                L=true;
            }
            
        }
        if(!N)
            r++;
        if(!S)
            r++;
        if(!U)
            r++;
        if(!L)
            r++;
        return r>req?r:req;
         
    }

    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();
    }
}