#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
typedef double T;
const double PI = 3.1415926535;
const double EPS = 0.0000001;
struct P {
T x, y;
P() : x(0), y(0){}
P(T x, T y) : x(x), y(y) {}
P operator +(P p){
return P(x+p.x,y+p.y);
}
P operator -(P p){
return P(x-p.x,y-p.y);
}
P operator *(T t){
return P(x*t, y*t);
}
P operator /(T t){
return P(x,y) * (1.0/t);
}
T dist(){
return sqrt(x*x+y*y);
}
T angle(){
return atan2(y,x);
}
P rotate(T angle){
double c = cos(angle);
double s = sin(angle);
return P(c*x-s*y,s*x+c*y);
}
};
double get(){
double r;
cin >> r;
r += (double)((rand() % 2000) - 1000) / 20000000.0;
return r;
}
double ang;
int wind(P a1, P b1){
// 0, 1, -1 if it crosses y = tan(ang) * x
P a = a1.rotate(-ang);
P b = b1.rotate(-ang);
if((a-b).dist() < EPS) return 0;
if(a.y > 0 && b.y > 0) return 0;
if(a.y < 0 && b.y < 0) return 0;
double nx = a.x + (0.0 - a.y) / (b.y - a.y) * (b.x - a.x);
if(nx < 0) return 0;
if(a.y < b.y) return 1;
return -1;
}
double S;
int bad(P a, P b){
// check if this intersects
// [-S, S] cross S
a.y -= S;
b.y -= S;
if((a-b).dist() < EPS) return 0;
if(a.y > 0 && b.y > 0) return 0;
if(a.y < 0 && b.y < 0) return 0;
double nx = a.x + (0.0 - a.y) / (b.y - a.y) * (b.x - a.x);
return (nx >= -S) && (nx <= S);
}
int ok(P a, P b){
if(bad(a.rotate(0),b.rotate(0))) return 0;
if(bad(a.rotate(PI/2.0), b.rotate(PI/2.0))) return 0;
if(bad(a.rotate(2.0*PI/2.0), b.rotate(2.0*PI/2.0))) return 0;
if(bad(a.rotate(3.0*PI/2.0), b.rotate(3.0*PI/2.0))) return 0;
return 1;
}
double dot(P a, P b){
return a.x*b.x + a.y*b.y;
}
pair<double,int> dist[250][250][2];
void join(int a, int b, int w, double len){
if(dist[a][b][0].second == w){
dist[a][b][0].first = min(dist[a][b][0].first, len);
} else if(dist[a][b][1].second == w){
dist[a][b][1].first = min(dist[a][b][1].first, len);
} else if(len < dist[a][b][1].first){
dist[a][b][1] = {len, w};
}
if(dist[a][b][0] > dist[a][b][1]){
swap(dist[a][b][0], dist[a][b][1]);
}
}
int main(){
ang = 0.001;
int n;
cin >> n >> S;
vector<pair<P,P> > segs;
vector<pair<int,int> > idx;
for(int i = 0; i < n; i++){
P a, b;
a.x = get(); a.y = get(); b.x = get(); b.y = get();
segs.push_back({a,b});
}
segs.push_back({P(S,S),P(S,S)});
segs.push_back({P(S,-S),P(S,-S)});
segs.push_back({P(-S,S),P(-S,S)});
segs.push_back({P(-S,-S),P(-S,-S)});
S -= 0.0001;
// get from each point to each other point with nonzero winding number.
// winding number adds one when
P origin = P(0,0);
vector<P> pts;
for(int i = 0; i < segs.size(); i++){
idx.push_back({pts.size(), pts.size()+1});
pts.push_back(segs[i].first);
pts.push_back(segs[i].second);
}
vector<pair<int,int> > edges;
vector<int> winds;
vector<double> length;
for(int i = 0; i < pts.size(); i++){
for(int j = 0; j < pts.size(); j++){
if( !ok(pts[i], pts[j]) ) continue;
edges.push_back({i,j});
winds.push_back( wind(pts[i],pts[j]) );
length.push_back((pts[i]-pts[j]).dist());
}
}
for(int i = 0; i < pts.size(); i++){
for(int j = 0; j < segs.size(); j++){
P p1 = segs[j].first - pts[i];
P p2 = segs[j].second - pts[i];
if((p1-p2).dist() < EPS) continue;
double len = dot(p2-p1, origin-p1) / (p2-p1).dist();
P r = p1 + (p2 - p1) * (len) / (p2-p1).dist();
if((p1-r).dist() + (p2-r).dist() > (p1-p2).dist() + EPS){
continue;
}
if( !ok(pts[i], pts[i] + r) ) continue;
double cost = r.dist();
edges.push_back({i,idx[j].first});
winds.push_back( wind(pts[i], pts[i] + r) + wind(pts[i] + r, pts[idx[j].first]) );
length.push_back(cost);
edges.push_back({idx[j].first, i});
winds.push_back( -winds[winds.size()-1] );
length.push_back(cost);
}
}
for(int i = 0; i < segs.size(); i++){
assert(ok(segs[i].first, segs[i].second));
edges.push_back({idx[i].first, idx[i].second});
winds.push_back(wind(segs[i].first, segs[i].second));
length.push_back(0.0);
edges.push_back({idx[i].second, idx[i].first});
winds.push_back(wind(segs[i].second, segs[i].first));
length.push_back(0.0);
}
double ans = 200000.0;
for(int i = 0; i < pts.size(); i++){
for(int j = 0; j < pts.size(); j++){
dist[i][j][0] = {200000.0, 0};
dist[i][j][1] = {200000.0, 1};
}
}
for(int i = 0; i < edges.size(); i++){
join(edges[i].first, edges[i].second, winds[i], length[i]);
}
for(int k = 0; k < pts.size(); k++){
for(int i = 0; i < pts.size(); i++){
for(int j = 0; j < pts.size(); j++){
for(int q = 0; q < 4; q++){
join(i, j, dist[i][k][q/2].second + dist[k][j][q%2].second,
dist[i][k][q/2].first + dist[k][j][q%2].first);
}
}
}
}
for(int i = 0; i < pts.size(); i++){
if(dist[i][i][0].second != 0){
ans = min(ans, dist[i][i][0].first);
}
if(dist[i][i][1].second != 0){
ans = min(ans, dist[i][i][1].first);
}
}
printf("%.10lf\n", ans);
}
