#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define siz(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//mt19937 mt;void random_start(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
//ll los(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9+7;
const ld eps = 0.02137;
struct edge
{
int v;
ld dist;
int is;
};
int n;
ld S;
pair<ld,ld> points[210];
vector<edge> graph[210];
bool odw[210][2];
ld dist[210][2];
bool is_inter_S(ld x1, ld y1, ld x2, ld y2, ld x3, ld y3, ld x4, ld y4)
{
if(y3 != y4)
{
swap(x1,y1);
x1 *= -1;
swap(x2,y2);
x2 *= -1;
swap(x3,y3);
x3 *= -1;
swap(x4,y4);
x4 *= -1;
}
if(x1 == x2) return x1 > min(x3,x4) && x1 < max(x3,x4) && y3 > min(y1,y2) && y3 < max(y1,y2);
if(y1 == y2) return 0;
ld b1 = (y1*x2-y2*x1)/(x2-x1);
ld a1 = 0;
if(x1 != 0) a1 = (y1-b1)/x1;
else a1 = (y2-b1)/x2;
ld b2 = y3;
ld a2 = 0;
ld x = (b2-b1)/(a1-a2);
return min(x1,x2) < x && x < max(x1,x2) && min(x3,x4) < x && x < max(x3,x4);
}
bool is_valid(ld x1, ld y1, ld x2, ld y2)
{
return !is_inter_S(x1,y1,x2,y2,-S,S-eps,S,S-eps)&&!is_inter_S(x1,y1,x2,y2,-S,-S+eps,S,-S+eps)&&!is_inter_S(x1,y1,x2,y2,S-eps,-S,S-eps,S)&&!is_inter_S(x1,y1,x2,y2,-S+eps,-S,-S+eps,S);
}
pair<ld,ld> opt_point(ld x1, ld y1, ld x2, ld y2, ld x3, ld y3)
{
ld A,B,C;
if(x1 != x2)
{
ld b1 = (y1*x2-y2*x1)/(x2-x1);
ld a1 = 0;
if(x1 != 0) a1 = (y1-b1)/x1;
else a1 = (y2-b1)/x2;
A = a1;
B = -1;
C = b1;
}
else
{
A = 1;
B = 0;
C = -x1;
}
ld opt_x = x3-A*((A*x3+B*y3+C)/(A*A+B*B));
ld opt_y = y3-B*((A*x3+B*y3+C)/(A*A+B*B));
if(opt_x < min(x1,x2) || opt_x > max(x1,x2) || opt_y < min(y1,y2) || opt_y > max(y1,y2)) return {x1,y1};
return {opt_x,opt_y};
}
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//random_start();
cin >> n >> S;
rep(i,n)
{
cin >> points[i*2].ff >> points[i*2].ss >> points[i*2+1].ff >> points[i*2+1].ss;
bool is = is_inter_S(points[i*2].ff,points[i*2].ss,points[i*2+1].ff,points[i*2+1].ss,0,eps,1e6,eps);
graph[i*2].pb({i*2+1,0,is});
graph[i*2+1].pb({i*2,0,is});
}
points[n*2] = {S,S};
points[n*2+1] = {S,-S};
points[n*2+2] = {-S,-S};
points[n*2+3] = {-S,S};
vector<pair<ld,ld>> pot;
rep2(i,n*2,n*2+3)
{
rep2(j,n*2,n*2+3)
{
if(i == j || abs(i-j) == 2) continue;
int is = is_inter_S(points[i].ff,points[i].ss,points[j].ff,points[j].ss,0,eps,1e6,eps);
graph[i].pb({j,2*S,is});
graph[j].pb({i,2*S,is});
}
}
rep2(i,0,n*2+3)
{
rep(s,n)
{
pot = {{points[s*2].ff,points[s*2].ss},{points[s*2+1].ff,points[s*2+1].ss},opt_point(points[s*2].ff,points[s*2].ss,points[s*2+1].ff,points[s*2+1].ss,points[i].ff,points[i].ss)};
pair<ld,int> min_d = {1e18,-1};
int ind = 0;
forall(it,pot)
{
if(is_valid(points[i].ff,points[i].ss,it.ff,it.ss)) min_d = min(min_d,{sqrtl((points[i].ff-it.ff)*(points[i].ff-it.ff)+(points[i].ss-it.ss)*(points[i].ss-it.ss)),ind});
ind++;
}
if(min_d.ff != 1e18)
{
int is = is_inter_S(points[i].ff,points[i].ss,pot[min_d.ss].ff,pot[min_d.ss].ss,0,eps,1e6,eps);
int is2 = is_inter_S(points[s*2].ff,points[s*2].ss,pot[min_d.ss].ff,pot[min_d.ss].ss,0,eps,1e6,eps);
int is3 = is_inter_S(points[s*2+1].ff,points[s*2+1].ss,pot[min_d.ss].ff,pot[min_d.ss].ss,0,eps,1e6,eps);
graph[i].pb({s*2,min_d.ff,(is^is2)});
graph[s*2].pb({i,min_d.ff,(is^is2)});
graph[i].pb({s*2+1,min_d.ff,(is^is3)});
graph[s*2+1].pb({i,min_d.ff,(is^is3)});
}
}
}
ld ans = 1e18;
priority_queue<pair<ld,pii>,vector<pair<ld,pii>>,greater<pair<ld,pii>>> pq;
rep2(v,0,n*2+3)
{
rep(i,n*2+4)
{
rep(d,2)
{
odw[i][d] = 0;
dist[i][d] = 1e18;
}
}
pq.push({0,{v,0}});
while(!pq.empty())
{
pair<ld,pii> t = pq.top();
pq.pop();
if(odw[t.ss.ff][t.ss.ss]) continue;
odw[t.ss.ff][t.ss.ss] = 1;
dist[t.ss.ff][t.ss.ss] = t.ff;
forall(it,graph[t.ss.ff])
{
pq.push({t.ff+it.dist,{it.v,t.ss.ss^it.is}});
}
}
ans = min(ans,dist[v][1]);
}
cout << fixed << setprecision(8) << ans << "\n";
}
