#include<stdio.h>
int main()
{
	int n, i, a, b, sum, min;
	i = 1;
	scanf("%d", &n);
	scanf("%d %d", &a, &b);
	if (n % a == 0)
		min = b * n / a;
	else
		min = b * (n / a + 1);
	while (i <= 2)
	{
		scanf("%d %d", &a, &b);
		if (n % a == 0)
			sum = b * n / a;
		else
			sum = b * (n / a + 1);
		if (min > sum)
			min = sum;
		i = i++;
	}
	printf("%d", min);
	return 0;
}