import java.util.Scanner;
public class Main{
    int price, num;
    public static int count(Main p,int n){
        if( n%p.num == 0 ) return n/p.num*p.price;
        else return (n/p.num+1)*p.price;
    }
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt(), priceMin = 0;
        Main[] pencile = new Main[4];
        for(int i=1; i<=3; i++){
            pencile[i].num = sc.nextInt();
            pencile[i].price = sc.nextInt();
            priceMin = ( priceMin < count(pencile[i],n) ? count(pencile[i],n) : priceMin );
        }
        System.out.print( priceMin );
    }
}