#include<bits/stdc++.h>
using namespace std;
int mininum,box,dozon,price,need;
int num=3;


int main()
{
   cin>>need;
   while(num--)
   {
       cin>>dozon>>price;
       while(box*dozon<need)box++;
       box+=1;
       if(box*price<mininum)mininum=box*dozon;
   }
   printf("%d",mininum);
   
    
    return 0;
}