#include<iostream>
#include<math.h>
using namespace std;
int main(){
    int a1,a2,b1,b2,c1,c2,n;
	cin>>n;
	cin>>a1>>a2;
	cin>>b1>>b2;
	cin>>c1>>c2;
    int a,b,c;
	a=a2*ceil(double(n)/a1);
	b=b2*ceil(double(n)/b1);
	c=c2*ceil(double(n)/c1);
	if(a>=b)
		cout<<int(b);
	else
		if(b>=c)
			cout<<int(c);
		else
			cout<<int(b);
	return 0;
}