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
#include <bits/stdc++.h>
using namespace std;
string alpha = "abcdefghijklmnopqrstuvwxyz";
const double PI = acos(-1);
const int N = 1e7 + 5;
long long int MOD = 1e9 + 7;
long long int OO = 1e18 + 8;
int oo = 1e9 + 9;
long long int pw(long long int b, long long int p) {
  if (!p) return 1;
  long long int sq = pw(b, p / 2);
  sq *= sq;
  if (p % 2) sq *= b;
  return sq;
}
long long int gcd(long long int a, long long int b) {
  return (b == 0 ? a : gcd(b, a % b));
}
long long int lcm(long long int a, long long int b) {
  return ((a * b) / gcd(a, b));
}
long long int PowMod(long long int bs, long long int ex, long long int M) {
  if (!ex) return 1;
  long long int p = PowMod((bs * bs) % M, ex >> 1, M);
  return (ex & 1) ? (p * bs) % M : p;
}
long long int ModInverse(long long int a) { return PowMod(a, MOD - 2, MOD); }
long long int ExtGCD(long long int a, long long int b, long long int& x,
                     long long int& y) {
  if (!b) {
    x = 1;
    y = 0;
    return a;
  }
  long long int r = ExtGCD(b, a % b, y, x);
  y -= a / b * x;
  return r;
}
long long int mult(long long int a, long long int b) {
  return (1LL * a * b) % MOD;
}
bool cmp(double a, double b) { return abs(a - b) < 1e-9; }
bool isint(double a) { return cmp(a, round(a)); }
bool isPrime(long long int n) {
  if (n == 2) return 1;
  if (n < 2 || n % 2 == 0) return 0;
  for (long long int i = 3; i * i <= n; i += 2)
    if (n % i == 0) return 0;
  return 1;
}
bool isPalindrome(string str) {
  long long int l = 0;
  long long int h = str.size() - 1;
  while (h > l) {
    if (str[l++] != str[h--]) {
      return 0;
    }
  }
  return 1;
}
bool isPerfectSquare(long double x) {
  long double sr = sqrt(x);
  return ((sr - floor(sr)) == 0);
}
double EucildDistance(double x, double y, double xx, double yy) {
  return sqrt((x - xx) * (x - xx) + (y - yy) * (y - yy));
};
int q;
int main() {
  std::ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  ;
  cin >> q;
  while (q--) {
    long long int n, m;
    cin >> n >> m;
    long long int a = n / m;
    long long int x = m;
    vector<long long int> c;
    c.push_back(x % 10);
    x += m;
    while (x % 10 != m % 10) c.push_back(x % 10), x += m;
    long long int b = a / c.size();
    long long int sum = 0;
    for (int i = 0; i < c.size(); i++) sum += c[i];
    sum *= b;
    b = a % c.size();
    for (int i = 0; i < b; i++) sum += c[i];
    cout << sum << '\n';
  }
  return 0;
}
