#include <bits/stdc++.h>
using namespace std;
const int Mod = 1e9 + 7;
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x * f;
}
const int lowbit(int x) { return x & -x; }
long long gcd(long long a, long long b) { return a == 0 ? b : gcd(b % a, a); }
bool vis[300007];
map<long long, int> make_pair;
string s, s1;
int a[300007] = {0}, b[300007] = {0}, c[300007] = {0}, set_g[300007] = {0},
    count1 = 0, i = 0, j = 0, ans = 0;
int h, n = 0, m, t = 0, k, v1, v2, maxx = -1, minn = 1000000000, cnt = 0,
       type = 0, temp = 1;
int aa = 0, bb = 1, cc = 0, x;
long long l1, l2;
int q, l, r;
set<int> se;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> q;
  ans += (2 * n + q - 1) / q;
  ans += (5 * n + q - 1) / q;
  ans += (8 * n + q - 1) / q;
  cout << ans;
  return 0;
}
