#import<bits/stdc++.h>
using namespace std;
typedef long double ld;
const int N=100013;
const ld inf=1e18;
int n,tt;
struct pt{
    int x,y;
    pt operator-(const pt&b)const{return{x-b.x,y-b.y};}
    bool operator<(const pt&b)const{return y<b.y;}
}p[N];
struct ln{
    pt x,y;
}l[N];
ld dp[N];
int sgn(int x){return!x?0:x>0?1:-1;}
int cr(pt x,pt y){return x.x*y.y-x.y*y.x;}
int f(pt a,pt b,pt c){return cr(c-a,c-b);}
bool isc(pt x,pt y,ln L){return sgn(f(x,y,L.x))*sgn(f(x,y,L.y))<0&&sgn(f(L.x,L.y,x))*sgn(f(L.x,L.y,y))<0;}
bool chk(pt x,pt y){for(int i=0;i<n;i++)if(isc(x,y,l[i]))return false;return true;}
ld slp(pt x,pt y){return fabsl((ld)(y.x-x.x)/(y.y-x.y));}
int main(){
    cout<<fixed<<setprecision(15);
    int m,v;
    cin>>n>>m>>v;
    for(int i=0,a,b,c,d;i<n;i++)
        cin>>a>>b>>c>>d,l[i]={{a,b},{c,d}},p[tt++]={a,b},p[tt++]={c,d};
    sort(p,p+tt);
    fill(dp,dp+tt,inf);
    ld ans=inf;
    if(chk({0,-10001},{0,10001}))ans=0;
    for(int i=0;i<tt;i++)if(abs(p[i].x)<m){
        if(chk({p[i].x,-10001},p[i]))dp[i]=0;
        for(int j=0;j<i;j++){
            if(p[i].y==p[j].y)break;
            if(chk(p[i],p[j]))dp[i]=min(dp[i],max(dp[j],slp(p[i],p[j])));
        }
        if(chk({p[i].x,10001},p[i]))ans=min(ans,dp[i]);
    }
    if(ans>1e17)cout<<-1<<'\n';
    else cout<<ans*v<<'\n';
}