#include <bits/stdc++.h>
using namespace std;
int q;
long long n, m;
vector<long long> a;
void solve() {
  a.clear();
  cin >> n >> m;
  int cur = 0;
  bool found = false;
  while (found == false) {
    long long tmp = m * (cur + 1);
    if (not a.empty())
      for (int i = 0; i <= a.size() - 1; i++)
        if (tmp % 10 == a[i] % 10) found = true;
    if (not found) {
      cur++;
      a.push_back(m * cur);
    }
  }
  long long sl = (n / m) / (long long)cur;
  long long s = 0;
  for (int i = 0; i < a.size(); i++) s += a[i] % 10;
  long long res = sl * s;
  int du = (n / m) % cur;
  for (int i = 0; i < du; i++) res += a[i] % 10;
  cout << res << endl;
}
int main() {
  cin >> q;
  for (int t = 1; t <= q; t++) {
    solve();
  }
}

### Prompt

Please provide a cpp coded solution 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 q;
long long n, m;
vector<long long> a;
void solve() {
  a.clear();
  cin >> n >> m;
  int cur = 0;
  bool found = false;
  while (found == false) {
    long long tmp = m * (cur + 1);
    if (not a.empty())
      for (int i = 0; i <= a.size() - 1; i++)
        if (tmp % 10 == a[i] % 10) found = true;
    if (not found) {
      cur++;
      a.push_back(m * cur);
    }
  }
  long long sl = (n / m) / (long long)cur;
  long long s = 0;
  for (int i = 0; i < a.size(); i++) s += a[i] % 10;
  long long res = sl * s;
  int du = (n / m) % cur;
  for (int i = 0; i < du; i++) res += a[i] % 10;
  cout << res << endl;
}
int main() {
  cin >> q;
  for (int t = 1; t <= q; t++) {
    solve();
  }
}

```