#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k, i, sum = 0;
  cin >> n >> k;
  for (i = 2; i <= 8; i += 3) {
    sum = sum + (i * n) / k;
    if ((i * n) % k != 0) sum += 1;
  }
  cout << sum;
  return 0;
}
