#include <bits/stdc++.h>
using namespace std;
int main() {
  int T;
  cin >> T;
  while (T--) {
    long long n, m;
    cin >> n >> m;
    if (m > n)
      cout << 0 << endl;
    else {
      int vis[20] = {0}, vis1[20] = {0};
      long long num = n / m;
      int flag = 0;
      long long sum = 0;
      for (int i = 1; i <= num; i++) {
        int a = (m * i) % 10;
        vis1[i] = a;
        if (vis[a])
          break;
        else
          vis[a]++;
        sum += a;
        flag++;
      }
      long long ans = (num / flag) * sum;
      if (num % flag != 0) {
        for (int i = 1; i <= num % flag; i++) {
          ans += vis1[i];
        }
      }
      cout << ans << endl;
    }
  }
  return 0;
}

### 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;
int main() {
  int T;
  cin >> T;
  while (T--) {
    long long n, m;
    cin >> n >> m;
    if (m > n)
      cout << 0 << endl;
    else {
      int vis[20] = {0}, vis1[20] = {0};
      long long num = n / m;
      int flag = 0;
      long long sum = 0;
      for (int i = 1; i <= num; i++) {
        int a = (m * i) % 10;
        vis1[i] = a;
        if (vis[a])
          break;
        else
          vis[a]++;
        sum += a;
        flag++;
      }
      long long ans = (num / flag) * sum;
      if (num % flag != 0) {
        for (int i = 1; i <= num % flag; i++) {
          ans += vis1[i];
        }
      }
      cout << ans << endl;
    }
  }
  return 0;
}

```