#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
int main(){
    int n,a1,b1,a2,b2,a3,b3,k,c1,c2,c3;
    cin>>n;
    	cin>>a1>>b1>>a2>>b2>>a3>>b3;
    	c1=(ceil(n*1.0/a1))*b1;
    	c2=(ceil(n*1.0/a2))*b2;
    	c3=(ceil(n*1.0/a3))*b3;
       
      if(c1>=c3&&c2>=c3){
      	k=c3;
      }
       if(c1<=c3&&c2>=c3){
      	k=c1;
      }
	   if(c1>=c3&&c2<=c3){
      	k=c2;
      }
      cout<<k;

	return 0;
	
}