import java.util.*;
import java.lang.*;
import java.io.*;

public class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		//your code here
                Scanner sc = new Scanner(System.in);
                   String a=sc.next();
                     long k = sc.nextLong();
              long n=0;
        for(int i=0;i<a.length();i++){
            n+=a.charAt(i)-'0';
        }
        n*=k;

               System.out.print (RDC(n,1));
        }

       public static long RDC( long n, long k){
                       long  ans = 0;
               while(n>0){
                       ans = n%10+ans;
                       n = n/10;
               }
               n = ans*k;
           if(n<10)return ans;
               return RDC(n,1);
       }
}