#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  int t;
  cin >> t;
  while (t > 0) {
    long long int n, m, i;
    cin >> n >> m;
    long long int k = (long long int)(n / m);
    int cycle[10];
    int sum = 0;
    for (i = 0; i < 10; i++) {
      cycle[i] = (m * (i + 1)) % 10;
      sum = sum + cycle[i];
    }
    long long int ans = 0;
    for (i = 0; i < k % 10; i++) {
      ans = ans + cycle[i];
    }
    ans = ans + (((long long int)(k / 10)) * sum);
    cout << ans << "\n";
    t--;
  }
}

### Prompt

Develop a solution in CPP to the problem described below:

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() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  int t;
  cin >> t;
  while (t > 0) {
    long long int n, m, i;
    cin >> n >> m;
    long long int k = (long long int)(n / m);
    int cycle[10];
    int sum = 0;
    for (i = 0; i < 10; i++) {
      cycle[i] = (m * (i + 1)) % 10;
      sum = sum + cycle[i];
    }
    long long int ans = 0;
    for (i = 0; i < k % 10; i++) {
      ans = ans + cycle[i];
    }
    ans = ans + (((long long int)(k / 10)) * sum);
    cout << ans << "\n";
    t--;
  }
}

```