#include<bits/stdc++.h>
using namespace std;
int n;
struct hhh
{
    int num;
    int money;
}a,b,c;
int main()
{
    int min;
    cin>>n;
    cin>>a.num>>a.money>>b.num>>b.money>>c.num>>c.money;
    int agreat=0,bgreat=0,cgreat=0;
    while(agreat*a.num<n)
        agreat++;
    while(bgreat*b.num<n)
        bgreat++;
    while(cgreat*c.num<n)
        cgreat++;
    agreat*=a.money;
    bgreat*=b.money;
    cgreat*=c.money;
    min=(agreat<bgreat)?((agreat<cgreat)?agreat:cgreat):((bgreat<cgreat)?bgreat:cgreat);
    cout<<min;
}