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
'''
    Auther: ghoshashis545 Ashis Ghosh
    College: jalpaiguri Govt Enggineering College

'''
from os import path
import sys
from heapq import heappush,heappop
from functools import cmp_to_key as ctk
from collections import deque,defaultdict as dd 
from bisect import bisect,bisect_left,bisect_right,insort,insort_left,insort_right
from itertools import permutations
from datetime import datetime
from math import ceil,sqrt,log,gcd
def ii():return int(input())
def si():return input().rstrip()
def mi():return map(int,input().split())
def li():return list(mi())
abc='abcdefghijklmnopqrstuvwxyz'
mod=1000000007
# mod=998244353
inf = float("inf")
vow=['a','e','i','o','u']
dx,dy=[-1,1,0,0],[0,0,1,-1]

def bo(i):
    return ord(i)-ord('a')

file = 1




    
def solve():

    # 0 1 2 3 4 5 6 7 8 9
    # 2 4 6 8 0 
    # 3 6 9 2 5 8 1 4 7 0
    # 4 8 2 6 0 
    # 5 0
    # 6 2 8 4 0 
    # 7 4 1 8 5 2 9 6 3 0
    # 8 6 4 2 0 
    # 9 
    for _ in range(ii()):

        n,m = mi()
        f = {}
        a = []
        for i in range(m,n+1,m):
            x = i%10
            if x not in f:
                f[x] = 1
                a.append(x)
            else:
                break
        for i in range(1,len(a)):
            a[i] += a[i-1]

        x = n//m
        if len(a) ==0 :
            print(0)
            continue
        
        x1 = x//len(a)
        x %= len(a)
        print(a[-1]*x1 + (a[x-1] if x>0 else 0))





        
if __name__ =="__main__":

    if(file):

        if path.exists('input.txt'):
            sys.stdin=open('input.txt', 'r')
            sys.stdout=open('output.txt','w')
        else:
            input=sys.stdin.readline
    solve()
