#include <bits/stdc++.h>
using namespace std;
int inf = (1e9) + 7;
int mod = 998244353;
int c(int num, int div) { return (num + div - 1) / div; }
int main() {
  int n, k;
  scanf("%d %d", &n, &k);
  int nr = 2 * n;
  int ng = 5 * n;
  int nb = 8 * n;
  printf("%d\n", c(nr, k) + c(ng, k) + c(nb, k));
}
