#include <bits/stdc++.h>
using namespace std;
long long n, ans;
string str;
long long solve() {
  long long q;
  cin >> q;
  vector<long long> v[10];
  for (long long i = 0; i <= 9; ++i) {
    for (long long j = 1; j <= 10; ++j) {
      v[i].push_back((i * j) % 10);
    }
  }
  long long s[10];
  for (long long i = 0; i <= 9; ++i) {
    s[i] = 0;
    for (long long j = 0; j <= 9; ++j) {
      s[i] += v[i][j];
    }
  }
  while (q--) {
    long long m;
    cin >> n >> m;
    long long k = n / m;
    m %= 10;
    long long x = 0;
    for (long long i = 0; i <= k % 10 - 1; ++i) {
      x += v[m][i];
    }
    cout << (k / 10) * s[m] + x << "\n";
  }
  return 0;
}
signed main() {
  ios::sync_with_stdio(0);
  long long t = 1;
  while (t--) solve();
  return 0;
}

### Prompt

Please create a solution in Cpp to 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;
long long n, ans;
string str;
long long solve() {
  long long q;
  cin >> q;
  vector<long long> v[10];
  for (long long i = 0; i <= 9; ++i) {
    for (long long j = 1; j <= 10; ++j) {
      v[i].push_back((i * j) % 10);
    }
  }
  long long s[10];
  for (long long i = 0; i <= 9; ++i) {
    s[i] = 0;
    for (long long j = 0; j <= 9; ++j) {
      s[i] += v[i][j];
    }
  }
  while (q--) {
    long long m;
    cin >> n >> m;
    long long k = n / m;
    m %= 10;
    long long x = 0;
    for (long long i = 0; i <= k % 10 - 1; ++i) {
      x += v[m][i];
    }
    cout << (k / 10) * s[m] + x << "\n";
  }
  return 0;
}
signed main() {
  ios::sync_with_stdio(0);
  long long t = 1;
  while (t--) solve();
  return 0;
}

```