1 #include <cmath>
2 #include <cstdio>
3 #include <iostream>
4 #include <algorithm>
5 #define N 2010
6 #define sqr(x) (x)*(x)
7 using namespace std;
8 struct node { int x,y; }p[N*3];
9 int n,px,py,qx,qy,num,a[10],x1[N],y3[N],x2[N],y2[N];
10 double P,dis[N*2];
11 void work()
12 {
13 num=1,p[1].x=px,p[1].y=py;
14 for (int i=1;i<n;i++)
15 if (px<=x2[i])
16 {
17 if (x2[i]>qx) break;
18 a[1]=y3[i],a[2]=y2[i],a[3]=y3[i+1],a[4]=y2[i+1],sort(a+1,a+4+1);
19 p[++num]=(node){x2[i],a[2]},p[++num]=(node){x2[i],a[3]};
20 }
21 p[++num]=(node){qx,qy};
22 }
23 int main()
24 {
25 scanf("%d",&n);
26 for (int i=1;i<=n;i++) scanf("%d%d%d%d",&x1[i],&y3[i],&x2[i],&y2[i]);
27 scanf("%d%d%d%d",&px,&py,&qx,&qy);
28 if (px>qx) swap(px,qx),swap(py,qy);
29 scanf("%lf",&P),work();
30 for (int i=2;i<=num;i++) dis[i]=1e99;
31 for (int i=1;i<=num;i++)
32 {
33 double X=(double)p[i].x*1.0,Y=(double)p[i].y*1.0,mx=1e99,mn=-1e99;
34 for (int j=i+1;j<=num;j++)
35 {
36 double xx=(double)p[j].x*1.0,yy=(double)p[j].y*1.0,len;
37 if (xx==X) { len=abs(Y-yy),dis[j]=min(dis[j],len+dis[i]); continue; }
38 double tmp=(yy-Y)/(xx-X);
39 if (tmp<=mx&&tmp>=mn)
40 {
41 double r=sqr(yy-Y)+sqr(xx-X);
42 len=sqrt(r),dis[j]=min(dis[j],len+dis[i]);
43 }
44 if (j%2==0) mn=max(mn,tmp); else mx=min(mx,tmp);
45 }
46 }
47 printf("%.10lf
",dis[num]/P);
48 }
