#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  unsigned long long int t;
  cin >> t;
  while (t--) {
    unsigned long long int n, m;
    cin >> n >> m;
    if (n < m) {
      cout << 0 << "\n";
      continue;
    }
    int rec = m % 10;
    int r[10], cum[10];
    r[0] = rec;
    cum[0] = rec;
    for (int i = 1; i < 10; i++) {
      r[i] = (r[i - 1] + rec) % 10;
      cum[i] = (cum[i - 1] + r[i]);
    }
    unsigned long long int comp = n / m;
    unsigned long long int t1 = comp / 10, t2 = comp % 10;
    unsigned long long int sum = 0;
    sum += (t1 * cum[9]);
    if (t2 != 0) sum += cum[t2 - 1];
    cout << sum << "\n";
  }
  return 0;
}

### Prompt

Create a solution in Cpp for 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() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  unsigned long long int t;
  cin >> t;
  while (t--) {
    unsigned long long int n, m;
    cin >> n >> m;
    if (n < m) {
      cout << 0 << "\n";
      continue;
    }
    int rec = m % 10;
    int r[10], cum[10];
    r[0] = rec;
    cum[0] = rec;
    for (int i = 1; i < 10; i++) {
      r[i] = (r[i - 1] + rec) % 10;
      cum[i] = (cum[i - 1] + r[i]);
    }
    unsigned long long int comp = n / m;
    unsigned long long int t1 = comp / 10, t2 = comp % 10;
    unsigned long long int sum = 0;
    sum += (t1 * cum[9]);
    if (t2 != 0) sum += cum[t2 - 1];
    cout << sum << "\n";
  }
  return 0;
}

```