#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long n, m;
  cin >> n >> m;
  vector<long long> a(10, 0), pr(10, 0);
  for (int i = 0; i < int(10); i++) {
    a[i] = (i ? (a[i - 1] + m) % 10 : 0);
    pr[i] = (i ? pr[i - 1] + a[i] : a[i]);
  }
  long long s = pr.back() + (a.back() + m) % 10;
  cout << (n / m / 10) * s + pr[(n / m) % 10] << endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  int n;
  cin >> n;
  for (int i = 0; i < int(n); i++) solve();
}

### Prompt

In cpp, your task is to solve the following problem:

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

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long n, m;
  cin >> n >> m;
  vector<long long> a(10, 0), pr(10, 0);
  for (int i = 0; i < int(10); i++) {
    a[i] = (i ? (a[i - 1] + m) % 10 : 0);
    pr[i] = (i ? pr[i - 1] + a[i] : a[i]);
  }
  long long s = pr.back() + (a.back() + m) % 10;
  cout << (n / m / 10) * s + pr[(n / m) % 10] << endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  int n;
  cin >> n;
  for (int i = 0; i < int(n); i++) solve();
}

```