#include <stdio.h>
#include <math.h>

int main()
{
	
	double h,s1,v,l,k,s2,s3,d,t;
	int num=0,n;

	scanf("%lf%lf%lf%lf%lf%d", &h, &s1, &v, &l, &k, &n);
 	d = h - k-0.0001;
	t = sqrt(d / 5);
	s2 = s1 - v * t;
	s3 = s2 + l;
	for (int i = 0; i <n; i++)
	{
		if (i >= s2 && i <= s3)
		{
			num++;
		}
	}
	printf("%d", num);
	return 0;
}