#include <cmath>
#include <cstdio>
#include <iostream>
using namespace std;
int n,tot,ans;
double h,s1,v,l,k;
int main()
{
	freopen("freefaller.in","r",stdin);
	freopen("freefaller.out","w",stdin);
	cin>>h>>s1>>v>>l>>k>>n;
	double t1=sqrt(2*h/10);
	double t2=sqrt(2*(h-k)/10);
	double Vmin=(s1-(n-1)-0.00001)/t1;
	double Vmax=(s1+l+0.00001)/t2;
	if(v<Vmin||v>Vmax)
		printf("%d\n",ans);
	else
	{
		for(int i=0;i<n;i++)
			if(i<=(s1-v*t2+l+0.00001)&&i>=(s1-v*t1-0.00001))
				tot++;
		printf("%d\n",tot);
	}
	return 0;
}