Polycarp is reading a book consisting of n pages numbered from 1 to n. Every time he finishes the page with the number divisible by m, he writes down the last digit of this page number. For example, if n=15 and m=5, pages divisible by m are 5, 10, 15. Their last digits are 5, 0, 5 correspondingly, their sum is 10.

Your task is to calculate the sum of all digits Polycarp has written down.

You have to answer q independent queries.

Input

The first line of the input contains one integer q (1 ≤ q ≤ 1000) — the number of queries.

The following q lines contain queries, one per line. Each query is given as two integers n and m (1 ≤ n, m ≤ 10^{16}) — the number of pages in the book and required divisor, respectively.

Output

For each query print the answer for it — the sum of digits written down by Polycarp.

Example

Input


7
1 1
10 1
100 3
1024 14
998244353 1337
123 144
1234312817382646 13


Output


1
45
153
294
3359835
0
427262129093995
/*
Stay innocent, be naive. 
But still dream big. 
Dream big to the point that it is beyond your ability and endeavour to achieve it. 
So dream big and don’t lose your innocence.
*/
import java.util.*;
import java.io.*;

   public class C
   {
      public static void main(String args[]) throws Exception
      {
         BufferedReader infile = new BufferedReader(new InputStreamReader(System.in));  
         StringTokenizer st = new StringTokenizer(infile.readLine());
         int Q = Integer.parseInt(st.nextToken());
         for(int qw=0; qw < Q; qw++)
         {
            st = new StringTokenizer(infile.readLine());
            long N = Long.parseLong(st.nextToken());
            long M = Long.parseLong(st.nextToken());
            //
            HashSet<Integer> set = new HashSet<Integer>();
            ArrayList<Integer> ls = new ArrayList<Integer>();
            long sum = 0L;
            int mul = 1;
            while(mul*M <= N)
            {
               int rem = (int)((mul*M)%10);
               if(set.contains(rem))
                  break;
               set.add(rem);
               ls.add(rem);
               sum += rem;
               mul++;
            }
            //
            if(set.size() == 0)
            {
               System.out.println(0);
               continue;
            }
            long K = N/M;
            long res = K/set.size();
            res *= sum;
            for(int i=0; i < (int)(K%set.size()); i++)
               res += ls.get(i);
            System.out.println(res);
         }
      }
   }