#include<iostream>
using namespace std;
int main() {
	long long money=10e10,lj=0,lj2=0;
	int a, b, c;
	cin >> a;
	for (int i = 0; i <3; i++)
	{
		cin >> b>> c;
		while (true)
		{
			lj += b;
			lj2 += c;
			if (lj >= a) {
				break;
			}
		}
	if (lj2 <=money) {
			money = lj2;
		}
	lj2 = 0;
	lj = 0;
	}
	cout << money;
}