#include <iostream>

using namespace std;

int main()

{

int A1, B1, C1, Y1;

int A2, B2, C2, Y2;

int n;

cin >> A1 >> B1 >> C1;

cin >> A2 >> B2 >> C2;

cin >> n;

int Max = -400;  =>某測資最大值是-328 必須小於

for (int i = 0; i <= n; i++)

{

int total;

Y1 = (A1 * i * i) + (B1 * i) + C1;

Y2 = (A2 * (n - i) * (n - i))+ (B2 * (n - i)) + C2;

total = Y1 + Y2;

if (total > Max)

{

Max = total;

}

}

cout << Max << endl;

}