#include<bits/stdc++.h>
using namespace std;
int main()
{
	double a,a1,b1,a2,b2,a3,b3,h,c1,c2,c3;
	cin>>a>>a1>>b1>>a2>>b2>>a3>>b3;
	c1=ceil(a/a1)*b1;
	c2=ceil(a/a2)*b2;
	c3=ceil(a/a3)*b3;
	h=c1;
	if(c2<h)
	  h=c2;
	if(c3<h)
	  h=c3;
	cout<<h;
	return 0;
}