#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n,a1,a2,a3,b1,b2,b3,c1,c2,c3;
	cin>>n>>a1>>b1>>a2>>b2>>a3>>b3;
	if (n%a1==0) {
		c1 = n/a1*b1;
	} else {
		c1 = (n/a1+1)*b1;
	}
	if (n%a2==0) {
		c2 = n/a2*b2;
	} else {
		c2 = (n/a2+1)*b2;
	}
	if (n%a3==0) {
		c3 = n/a3*b3;
	} else {
		c3 = (n/a3+1)*b3;
	}
	if (c1<c2&&c1<c3){
		cout<<c1; 
	} else if(c2<c1&&c2<c3){
		cout<<c2;
	}else{
		cout<<c3;
	}
}