#include <bits/stdc++.h>
using namespace std;
int q, i, j;
int a[10][11];
long long int n, m;
int main() {
  cin >> q;
  for (i = 1; i < 10; i++) {
    a[i][0] = 0;
    for (j = 1; j < 11; j++) {
      a[i][j] = a[i][j - 1] + (i * j) % 10;
    }
  }
  while (q > 0) {
    q--;
    long long int n, m;
    cin >> n >> m;
    if (m % 10 == 0) {
      cout << 0 << endl;
    } else {
      cout << ((n / m) / 10) * a[m % 10][10] + a[m % 10][(n / m) % 10] << endl;
    }
  }
}

### Prompt

Construct a cpp code solution to the problem outlined:

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 q, i, j;
int a[10][11];
long long int n, m;
int main() {
  cin >> q;
  for (i = 1; i < 10; i++) {
    a[i][0] = 0;
    for (j = 1; j < 11; j++) {
      a[i][j] = a[i][j - 1] + (i * j) % 10;
    }
  }
  while (q > 0) {
    q--;
    long long int n, m;
    cin >> n >> m;
    if (m % 10 == 0) {
      cout << 0 << endl;
    } else {
      cout << ((n / m) / 10) * a[m % 10][10] + a[m % 10][(n / m) % 10] << endl;
    }
  }
}

```