#include <bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define per(i, a, b) for(int i = b-1; i>=a ; i--)
#define trav(a, x) for(auto& a : x)
#define allin(a , x) for(auto a : x)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<ll> vl;
typedef vector<pii> vpi;
typedef pair<ll,ll> pll;
typedef vector<string> vs;
typedef vector<pll> vpl;
typedef vector<int> vi;
std::mt19937 rng((int) std::chrono::steady_clock::now().time_since_epoch().count());
template <class T> int sgn(T x) { return (x > 0) - (x < 0); }
template<class T>
struct Point {
typedef Point P;
T x, y;
explicit Point(T x=0, T y=0) : x(x), y(y) {}
bool operator<(P p) const { return tie(x,y) < tie(p.x,p.y); }
bool operator==(P p) const { return tie(x,y)==tie(p.x,p.y); }
P operator+(P p) const { return P(x+p.x, y+p.y); }
P operator-(P p) const { return P(x-p.x, y-p.y); }
P operator*(T d) const { return P(x*d, y*d); }
P operator/(T d) const { return P(x/d, y/d); }
T dot(P p) const { return x*p.x + y*p.y; }
T cross(P p) const { return x*p.y - y*p.x; }
T cross(P a, P b) const { return (a-*this).cross(b-*this); }
T dist2() const { return x*x + y*y; }
double dist() const { return sqrt((double)dist2()); }
// angle to x-axis in interval [-pi, pi]
double angle() const { return atan2(y, x); }
P unit() const { return *this/dist(); } // makes dist()=1
P perp() const { return P(-y, x); } // rotates +90 degrees
P normal() const { return perp().unit(); }
// returns point rotated 'a' radians ccw around the origin
P rotate(double a) const {
return P(x*cos(a)-y*sin(a),x*sin(a)+y*cos(a)); }
friend ostream& operator<<(ostream& os, P p) {
return os << "(" << p.x << "," << p.y << ")"; }
};
typedef Point<double> P;
P v[1000005];
int n , L;
double f(double x){
double ans = 0;
for(int i = 0 ; i < n; i ++){
P a(x,0);
ans = max(ans , (a-v[i]).dist());
}
return ans;
}
int32_t main(){
cin >> n >> L;
for(int i = 0 ; i < n; i ++)
cin >> v[i].x >> v[i].y;
double ans = DBL_MAX;
double l = 0.00 , r = L;
while(r-l > 1e-6){
double m1 = l + (r-l)/3;
double m2 = r - (r-l)/3;
if(f(m1) > f(m2)){
l = m1;
}
else{
r = m2;
}
}
cout << fixed << setprecision(6) << f(l) << endl;
}
