#include <bits/stdc++.h>
using namespace std;
using ull = unsigned long long;
vector<int> num[10];
int value[10];
void init() {
  for (int i = 0; i < 10; i++) {
    value[i] = i;
    num[i].emplace_back(i);
    int v = (i + i) % 10;
    while (v != i) {
      num[i].emplace_back(v);
      value[i] += v;
      v = (v + i) % 10;
    }
  }
}
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  init();
  int q;
  cin >> q;
  while (q--) {
    ull n, m;
    cin >> n >> m;
    ull ans = ((n / m) / num[m % 10].size()) * value[m % 10];
    ull left = (n / m) % num[m % 10].size();
    for (ull i = 0; i < left; i++) ans += num[m % 10][i];
    cout << ans << '\n';
  }
  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;
using ull = unsigned long long;
vector<int> num[10];
int value[10];
void init() {
  for (int i = 0; i < 10; i++) {
    value[i] = i;
    num[i].emplace_back(i);
    int v = (i + i) % 10;
    while (v != i) {
      num[i].emplace_back(v);
      value[i] += v;
      v = (v + i) % 10;
    }
  }
}
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  init();
  int q;
  cin >> q;
  while (q--) {
    ull n, m;
    cin >> n >> m;
    ull ans = ((n / m) / num[m % 10].size()) * value[m % 10];
    ull left = (n / m) % num[m % 10].size();
    for (ull i = 0; i < left; i++) ans += num[m % 10][i];
    cout << ans << '\n';
  }
  return 0;
}

```