#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>
#include<vector>
#include<queue>
#include<set>
#include<map>
#include<cmath>
using namespace std;
typedef long double ld;
const int N=110;
const ld pai=acos(-1.0);
struct node
{
	ld x,y;
}p0,p[N];
int n,d,T;
ld s[N<<1],s0;
int main()
{
	scanf("%d%Lf%Lf%d%d",&n,&p0.x,&p0.y,&d,&T);s0=atan2(p0.y,p0.x);
	for(int i=1;i<=n;i++)
	{
		scanf("%Lf%Lf",&p[i].x,&p[i].y);
		ld t=atan2(p[i].y,p[i].x),dt=atan2(d,sqrt(p[i].x*p[i].x+p[i].y*p[i].y-d*d));
		s[2*i-1]=t-dt,s[2*i]=t+dt;
	}
	ld L=pai*3.0,R=-pai*3.0;
	for(int i=1;i<=2*n;i++)
	{
		ld t=s[i];
		while(t<s0) t+=pai*2.0;
		L=min(L,t-s0),R=max(R,t-s0);
	}
//	printf("L=%.7Lf R=%.7Lf\n",L,R);
	ld ans=0;
	if((R-L)>=pai)
	{
		L=pai*3.0,R=-pai*3.0;
		for(int i=1;i<=2*n;i++)
		{
			ld t=s[i];
			while(t<s0-pai) t+=pai*2.0;
			while(t>s0+pai) t-=pai*2.0;
			L=min(L,t-s0),R=max(R,t-s0);
		}
		ld L1=0,R1=R,L2=pai*2.0+L,R2=pai*2.0;
		ld t1=floor(T/(pai*2.0)),t2=T-pai*2.0*t1;
		ans=t1*((R1-L1)+(R2-L2))+max((ld)0.0,min(t2,R1))+max((ld)0.0,t2-L2);
	}
	else
	{
		ld t1=floor(T/(pai*2.0)),t2=T-pai*2.0*t1;
		ans=t1*(R-L)+max((ld)0.0,min(t2,R)-L);
	}
	printf("%.12Lf\n",ans);
	return 0;
}