#include<stdio.h>
#include<algorithm>
#include<math.h>
using namespace std;
typedef long double lf;
int n,m,V,cp;
lf f[205],ans=1e9;
struct po{
	int x,y;
	po operator -(po a){return po{x-a.x,y-a.y};}
	bool operator <(const po a)const{return y<a.y;}
}p[205];
struct line{
	po a,b;
}l[105];
int cros(po a,po b){
	return a.x*b.y-a.y*b.x;
}
bool cros(line A,line B){
	return 1ll*cros(A.a-B.a,B.b-B.a)*cros(A.b-B.a,B.b-B.a)<0&&1ll*cros(B.a-A.a,A.b-A.a)*cros(B.b-A.a,A.b-A.a)<0;
}
bool check(line A){
	for(int i=1;i<=n;++i)if(cros(l[i],A))return false;
	return true;
}
int main(){
	scanf("%d%d%d",&n,&m,&V);
	for(int i=1;i<=n;++i){
		scanf("%d%d%d%d",&l[i].a.x,&l[i].a.y,&l[i].b.x,&l[i].b.y);
		p[++cp]=l[i].a,p[++cp]=l[i].b;
	}
	sort(p+1,p+cp+1);
	for(int i=1;i<=cp;++i)f[i]=1e9;
	for(int i=1;i<=cp;++i){
		if(abs(p[i].x)!=m&&check(line{p[i],po{p[i].x,(int)-2e4}}))f[i]=0;
		for(int j=i+1;j<=cp;++j)if(p[j].y!=p[i].y&&check(line{p[j],p[i]}))f[j]=min(f[j],max(f[i],fabsl(lf(p[i].x-p[j].x)/(p[i].y-p[j].y))));
		if(abs(p[i].x)!=m&&check(line{p[i],po{p[i].x,(int)2e4}}))ans=min(ans,f[i]);
	}
	if(ans>1e8)return puts("-1"),0;
	printf("%Lf\n",ans*V);
	return 0;
}