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 $q$ ($1 \le q \le 1000$) — the number of queries.

The following $q$ lines contain queries, one per line. Each query is given as two integers $n$ and $m$ ($1 \le n, m \le 10^{16}$) — 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

```python

USER_FILENAME = "<user_code>"
import sys, json, builtins
import math, heapq, bisect, itertools, functools, collections, statistics, fractions, decimal, operator, array, random, re, string, os, pathlib
try:
    import resource as _res
except Exception:
    _res = None
from collections import Counter, defaultdict, deque, OrderedDict
from functools import lru_cache, reduce
from itertools import accumulate, permutations, combinations, product
from math import gcd, ceil, floor, sqrt
from decimal import Decimal
try:
    from typing import *
except Exception:
    pass
try:
    sys.setrecursionlimit(1_000_000)
except Exception:
    pass
try:
    import site as _site
    try:
        _sys_sites = _site.getsitepackages() if hasattr(_site, "getsitepackages") else []
        for _p in _sys_sites:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
    try:
        _usp = _site.getusersitepackages()
        if isinstance(_usp, str):
            _usp = [_usp]
        for _p in _usp:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
except Exception:
    pass

ns = {"__name__": "__main__"}
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = '# TAIWAN NUMBER ONE!!!!!!!!!!!!!!!!!!!\n# TAIWAN NUMBER ONE!!!!!!!!!!!!!!!!!!!\n# TAIWAN NUMBER ONE!!!!!!!!!!!!!!!!!!!\nfrom sys import stdin, stdout\nfrom collections import defaultdict\nfrom collections import deque\nimport math\nimport copy\n \nT = int(input())\n#N = int(input())\n#s1 = input()\n#s2 = input()\n#N,Q = [int(x) for x in stdin.readline().split()]\n#arr = [int(x) for x in stdin.readline().split()]\n\nfor i in range(T):\n    N,M = [int(x) for x in stdin.readline().split()]\n    \n    d = M%10\n    \n    q = N//M\n    \n    tail = []\n    \n    t = 0\n    while True:\n        t = (t + d)%10\n        if t not in tail:\n            tail.append(t)\n        else:\n            break\n            \n    L = len(tail)\n    \n    s = sum(tail)\n    q2 = q//L\n    r = q%L\n    \n    #print(q2,r)\n    print(q2*s+sum(tail[:r]))'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 178136