#include<stdio.h>
int main()
{
	int a, b, c;
	scanf("%d", &c);
	int num = 1e7;
	int i;
	int d;
	for (i = 1;i <= 3;i++)
	{
		scanf("%d %d", &a, &b);
		if (c%a == 0)
		{
			d = c / a;
			if (d*b < num)
				num = d * b;
		}
		else
		{
			d = c / a;
			if ((d + 1)*b < num)
				num = (d + 1)*b;
		}
	}
		printf("%d", num);
		return 0;
}