#include<iostream>
#include<cmath>
using namespace std;
int main() {
	int n,x1,p1,x2,p2,x3,p3,t1,t2,t3,ans;
	cin >> n >> x1 >> p1 >> x2 >> p2 >> x3 >> p3;
	t1 = ceil(n/x1)*p1;
	t2 = ceil(n/x2)*p2;
	t3 = ceil(n/x3)*p3;
	ans = t1;
	if (t2<ans)ans = t2;
	if (t3<ans)ans = t3;
	cout << ans << endl;
	return 0;
}