#include<cmath>
#include<cstdio>
#include<algorithm>
int n,a,b,c,ans=2100000000,x,i;
int main()
{
   
    scanf("%d",&n);
    for (;i<3;i++)
    {
   
        scanf("%d%d",&a,&b);
        x=std::ceil(n*1.0/a)*b;
        ans=std::min(x,ans);
    }
    printf("%d\n",ans);
    return 0;
}


#include<bits/stdc++.h>
using namespace std;
	long n,a1,a2,b1,b2,c1,c2;
	long pen1=0,pen2=0,pen3=0;
	long x[3];
int main(){
   

	cin>>n>>a1>>a2>>b1>>b2>>c1>>c2;;
	while(pen1<n){
   
		pen1+=a1;
		x[0]+=a2;
	} 
	while(pen2<n){
   
		pen2+=b1;
		x[1]+=b2;
	}
	while(pen3<n){
   
		pen3+=c1;
		x[2]+=c2;
	}
	sort(x,x+3);
	cout<<x[0];
	return 0;
}