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
//package godiji;
//|__|  /_\   /_\  |\ |
//|  | /   \ /   \ | \|

//|__|  /_\   /_\  |\ |
//|  | /   \ /   \ | \|
import java.util.Scanner;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;

public class pac1 {
	static Scanner scn = new Scanner(System.in);
	static int count = 0;

	public static void main(String[] args) throws Exception {
		// enter the size of arra
		//haan haan chutiya katva lia faltu m
		int t=scn.nextInt();
		while(t-->0)
		{
		long n=scn.nextLong(),k=scn.nextLong();
		long rem=0,div=n/k,sum=0,count=0,l=0;
		
		if(n<k)
			System.out.println("0");
		else
		{
			long arr[]=new long[11];
			for(int i=1;i<=10;i++) 
			{
				arr[i]= (arr[i-1]+k);
				sum+=arr[i]%10;
			}
			//System.out.println(sum);
			if(div>10)
			{
				sum= sum*(div/10);
				//System.out.println(sum);
				rem=div%10;
				for(int i=1;i<=rem;i++)
					sum+=arr[i]%10;
				//System.out.println(sum);
			}
			else
			{	sum=0;
				for(int i=1;i<=div;i++)
					sum+=arr[i]%10;
			}
			System.out.println(sum);
		}
		}
	}
	
	
	

	public static long gcd(long a, long n) {

		if (a == 0)
			return n;
		return gcd(n % a, a);
	}
}
class Point 
{
	int x;
	int y;
	
	Point(int a, int b)
	{
		x=a;
		y=b;
	}
}
 
class sortingPoint implements Comparator<Point>
{
	public int compare(Point p1, Point p2)
	{
		if(p1.x==p2.x) return p1.y-p2.y;
		else return p1.x-p2.x;
	}
}
