#include<iostream>
#include <climits>
using namespace std;
int main(){
int a1, b1, c1, a2, b2, c2, n;
cin >> a1 >> b1 >> c1 >> a2 >> b2 >> c2 >> n;
int ans=-INT_MAX;
for (int x1=0; x1<=n; x1++){
int x2=n-x1;
int y1=a1*x1*x1+b1*x1+c1;
int y2=a2*x2*x2+b2*x2+c2;
ans=max(ans, y1+y2);
}
cout << ans <<endl;
}