#include<iostream>
using namespace std;
int main() {
	int n,a1,b1,a2,b2,a3,b3,bag1,bag2,bag3,sum1,sum2,sum3,sum;
	cin>>n;
	cin>>a1>>b1;
	cin>>a2>>b2;
	cin>>a3>>b3;
	if(n%a1==0)
	bag1=n/a1;
	else{
	bag1=n/a1+1;
}
	sum1=b1*bag1;
	
	if(n%a2==0)
	bag2=n/a2;
	else{
	bag2=n/a2+1;
	}
	sum2=b2*bag2;
	
	if(n%a3==0)
	bag3=n/a3;
	else{
	bag3=n/a3+1;
	}
	sum3=b3*bag3;
	
	if(sum1<sum2&&sum1<sum3)
	sum=sum1;
	if(sum2<sum1&&sum2<sum3)
	sum=sum2;		
	if(sum3<sum2&&sum3<sum1)
	sum=sum1;
	cout<<sum<<endl;
    return 0;
}