#include <bits/stdc++.h>
int main(int argc, char **argv) {
  int x, y;
  scanf("%d %d", &x, &y);
  printf("%d",
         ((x * 2 - 1) / y + 1) + ((x * 5 - 1) / y + 1) + ((x * 8 - 1) / y + 1));
  return 0;
}
