#include<iostream>
#include<cmath>
using namespace std;
int main(){
    int s,l1,l2,l3,m1,m2,m3;
    cin>>s;
    cin>>l1>>m1;
    cin>>l2>>m2;
    cin>>l3>>m3;
    int mm1=ceil(s/l1)*m1,mm2=ceil(s/l2)*m2,mm3=ceil(s/l3)*m3;
    cout<<min(min(mm1,mm2),mm3);
    return 0;
}