#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pi pair<int,int>
#define vi vector<int>
#define rep(i,x,n) for(int i=x; i<n; ++i)
#define For(i,n) rep(i,0,n)
#define endl "\n"
#define sp ' '
#define pb push_back
#define f first
#define s second
#define sz size()
#define all(x) (x).begin(),(x).end()
const int N = 1e6+1, OO = 1e18, mod = 1e9;
void tr(int a, int b){cout << a << sp << b << endl;}
void cmx(double &a, double b){a = max(a,b);}
void cmn(double &a, double b){a = min(a,b);}
pi p[N];
deque <pi> v, u;
int n,l;
double mn1 = OO, mn2 = OO, ans = 0;
int fun(int j){
if(u.sz == 1) return j ? -OO: OO;
int X = abs(u[0].f - u[1].f);
int d = ( u[0].s * u[0].s - u[1].s * u[1].s + X * X ) / (-2*X);
return d;
}
void deb(){
deque <pi> t;
For(i,n){
int j = i, mn = OO;
while(j < n && v[i].f == v[j].f) mn = min(mn, v[j].s), j++;
t.pb(v[i]);
i = j-1;
}
v = t; n = v.sz;
}
double calc(pi L, pi R){
double X = abs(R.f - L.f);
if(L.s*L.s + X*X <= R.s*R.s) return sqrt(L.s*L.s + X*X);
if(R.s*R.s + X*X <= L.s*L.s) return sqrt(R.s*R.s + X*X);
double d = ( R.s * R.s - L.s * L.s + X*X ) / (2*X), dist = sqrt(d*d + L.s*L.s);
if(R.f >= 0 && L.f >= 0){
return dist;
}
if(R.f > l && L.f <= l){
if(L.f + d < l)
return dist;
}
if(L.f < 0 && R.f >= 0){
if(R.f - d > 0)
return dist;
}
return 0;
}
int32_t main() {
ios::sync_with_stdio(0); cin.tie(0);
cin >> n >> l;
For(i,n){
int x,y; cin >> x >> y;
y = abs(y);
v.pb({x,y});
}
deb();
u.pb(v[0]);
for(int i=1; i<n; ++i){
auto [x,y] = v[i];
while(u.sz > 1 && fun(0) + u.front().f < x){
u.pop_front();
while(fun(0) < 0) u.pop_front();
}
while(u.sz && u.back().s * u.back().s >= (abs(x-u.back().f)*abs(x-u.back().f) + y*y)) u.pop_back();
p[i-1] = u.front();
if(u.sz && abs(u.front().f-x) * abs(u.front().f-x) + u.front().s * u.front().s <= y*y){
u.pb(v[i]);
} else {
u.clear();
u.pb(v[i]);
}
} u.clear();
for(auto [x,y]: v){
cmn(mn1, sqrt(x*x+y*y));
cmn(mn2, sqrt(abs(x-l)*abs(x-l)+y*y));
}
cmx(ans, max(mn1,mn2));
u.pb(v[n-1]);
for(int i=n-2; i>=0; --i){
auto [x,y] = v[i];
while(u.sz > 1 && -fun(1) + u.front().f > x){
u.pop_front();
while(fun(1) > 0) u.pop_front();
}
while(u.sz && u.back().s * u.back().s >= (abs(x-u.back().f)*abs(x-u.back().f) + y*y)) u.pop_back();
cmx(ans,calc(p[i], u.front()));
if(u.sz && abs(u.front().f-x) * abs(u.front().f-x) + u.front().s * u.front().s <= y*y){
u.pb(v[i]);
}else {
u.clear();
u.pb(v[i]);
}
}
cout << fixed << setprecision(4) << ans << endl;
return 0;
}
/*
7 14
2 1
3 3
4 3
7 5
11 3
12 2
14 0
*/
