#include<iostream>
#include<cmath>
#include<algorithm>
using namespace std;
int main()
{
    double c[3]={};
    double a,b,n;
    cin>>n;
    for (int i=0;i<3;i++)
    {
        cin>>a>>b;
        c[i]=ceil(n/a)*b;
    }
    cout<<*min_element(c,c+3)<<endl;
}