很簡單的題意。。。

#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<string.h>
#include<queue>
#include<stack>
#include<list>
#include<map>
#include<set>
#include<vector>
using namespace std;
typedef long long int ll;
const int maxn =1e6+5;
const int maxm=10000;
const int mod =1e9+7;
const int INF=0x3f3f3f3f;
const double eps=1e-8;

int main()
{
	int n,k;scanf("%d%d",&n,&k);
	printf("%d\n",(2*n%k==0?2*n/k:2*n/k+1)+(5*n%k==0?5*n/k:5*n/k+1)+(8*n%k==0?8*n/k:8*n/k+1));
    return 0;
}