#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long n, m;
  cin >> n >> m;
  long long x = n / m, ans = 0;
  vector<long long> v;
  for (long long i = 1; i <= 10; i++) v.push_back((i * m) % 10);
  for (long long i = 0; i < 10; i++) ans += v[i];
  ans *= x / 10;
  for (long long i = 0; i < x % 10; i++) ans += v[i];
  cout << ans << "\n";
  return;
}
int32_t main() {
  long long test;
  cin >> test;
  while (test--) {
    solve();
  }
  return 0;
}

### 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;
void solve() {
  long long n, m;
  cin >> n >> m;
  long long x = n / m, ans = 0;
  vector<long long> v;
  for (long long i = 1; i <= 10; i++) v.push_back((i * m) % 10);
  for (long long i = 0; i < 10; i++) ans += v[i];
  ans *= x / 10;
  for (long long i = 0; i < x % 10; i++) ans += v[i];
  cout << ans << "\n";
  return;
}
int32_t main() {
  long long test;
  cin >> test;
  while (test--) {
    solve();
  }
  return 0;
}

```