#include<bits/stdc++.h>
using namespace std;
double n,a1,a2,a3,b1,b2,b3,sum1=0,sum2=0,sum3=0;
int main(){
	cin>>n;
	cin>>a1>>b1>>a2>>b2>>a3>>b3;
	sum1=ceil(n/a1)*b1;
	sum2=ceil(n/a2)*b2;
	sum3=ceil(n/a3)*b3;
	cout<<min(sum1,min(sum2,sum3));
	return 0;
}