// dfmt off
T lread(T=long)(){return readln.chomp.to!T;}T[] lreads(T=long)(long n){return iota(n).map!((_)=>lread!T).array;}
T[] aryread(T=long)(){return readln.split.to!(T[]);}void arywrite(T)(T a){a.map!text.join(' ').writeln;}
void scan(L...)(ref L A){auto l=readln.split;foreach(i,T;L){A[i]=l[i].to!T;}}alias sread=()=>readln.chomp();
void dprint(L...)(lazy L A){debug{auto l=new string[](L.length);static foreach(i,a;A)l[i]=a.text;arywrite(l);}}
static immutable MOD=10^^9+7;alias PQueue(T,alias l="b<a")=BinaryHeap!(Array!T,l);import std, core.bitop;
// dfmt on

void main()
{
    long Q, H, S, D;
    scan(Q, H, S, D);
    long N = lread();
    N *= 4;
    long solve(long x)
    {
        if (x == 0)
            return 0;
        long ret = long.max;
        if (8 <= x)
            ret = ret.min((x / 8) * D + solve(x % 8));
        if (4 <= x)
            ret = ret.min((x / 4) * S + solve(x % 4));
        if (2 <= x)
            ret = ret.min((x / 2) * H + solve(x % 2));
        if (1 <= x)
            ret = ret.min((x / 1) * Q + solve(x % 1));
        return ret;
    }

    solve(N).writeln();
}
