Problem:
Score : 300 points

Problem Statement

You've come to your favorite store Infinitesco to buy some ice tea.

The store sells ice tea in bottles of different volumes at different costs.
Specifically, a 0.25-liter bottle costs Q yen, a 0.5-liter bottle costs H yen, a 1-liter bottle costs S yen, and a 2-liter bottle costs D yen.
The store has an infinite supply of bottles of each type.

You want to buy exactly N liters of ice tea. How many yen do you have to spend?

Constraints

1 \leq Q, H, S, D \leq 10^8

1 \leq N \leq 10^9

All input values are integers.

Input

Input is given from Standard Input in the following format:

Q H S D
N

Output

Print the smallest number of yen you have to spend to buy exactly N liters of ice tea.

Sample Input 1

20 30 70 90
3

Sample Output 1

150

Buy one 2-liter bottle and two 0.5-liter bottles. You'll get 3 liters for 90 + 30 + 30 = 150 yen.

Sample Input 2

10000 1000 100 10
1

Sample Output 2

100

Even though a 2-liter bottle costs just 10 yen, you need only 1 liter.
Thus, you have to buy a 1-liter bottle for 100 yen.

Sample Input 3

10 100 1000 10000
1

Sample Output 3

40

Now it's better to buy four 0.25-liter bottles for 10 + 10 + 10 + 10 = 40 yen.

Sample Input 4

12345678 87654321 12345678 87654321
123456789

Sample Output 4

1524157763907942

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef pair<int,int> P;
typedef pair<ll,ll> PL;

#define INF 1<<30
#define LINF 1ll<<60ll
#define MOD 1000000007
#define pb(a) push_back(a)

#define _overload3(_1,_2,_3,_4,name,...) name
#define _rep(i,n) _repi(i,0,n)
#define _repi(i,a,b) for(int i=a, i##_len=(b); i<i##_len; ++i)
#define _repis(i,a,b,s) for(int i=a, i##_len(b); i<i##_len; i+=s)
#define REP(...) _overload3(__VA_ARGS__,_repis,_repi,_rep,)(__VA_ARGS__)

#define REPR(i, n) for(int i = n;i >= 0;--i)
#define REPARR(i, v) for(int i = 0;i < sz(v);++i)

#define all(vec) (vec.begin()),(vec.end())
#define sz(x) ((int)(x).size())
#define bit(n) (1ll<<(n))

template<class T>bool chmax(T &a,const T &b){if(a<b){a=b;return true;}return false;}
template<class T>bool chmin(T &a,const T &b){if(a>b){a=b;return true;}return false;}

#define YES(n) cout<<((n)?"YES":"NO")<<endl
#define Yes(n) cout<<((n)?"Yes":"No")<<endl
#define yes(n) cout<<((n)?"yes":"no")<<endl
#define poss(n) cout<<((n)?"possible":"impossible")<<endl
#define Poss(n) cout<<((n)?"Possible":"Impossible")<<endl
#define POSS(n) cout<<((n)?"POSSIBLE":"IMPOSSIBLE")<<endl



int main(){
    ll q,h,s,d;
    cin>>q>>h>>s>>d;
    if(q*2<h)h=q*2;
    if(h*2<s)s=h*2;
    if(s*2<d)d=s*2;
    ll n;
    cin>>n;
    cout<<(n/2)*d+(n%2)*s<<endl;
    return 0;
}