#include<bits/stdc++.h> using namespace std; const int MAXN=1e6+5; long long X[MAXN],Y[MAXN]; double dist(double xa,double ya,double xb,double yb) { return sqrt((xa-xb)*(xa-xb)+(ya-yb)*(ya-yb)); } double getl(double x,double y,double k) { return x-sqrt(k*k-y*y); } double getr(double x,double y,double k) { return x+sqrt(k*k-y*y); } int main() { ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); int n,len; cin>>n>>len; for(int i=1;i<=n;i++) cin>>X[i]>>Y[i]; double l=0,r=2e9,ans=2e9; for(int i=1;i<=n;i++) l=max(l,(double)Y[i]); while(r-l>1e-5) { double mid=(l+r)/2,mx=0,mt=0; for(int i=1;i<=n;i++) if(getl(X[i],Y[i],mid)<=mx) { mx=max(mx,getr(X[i],Y[i],mid)); mx=max(mx,mt),mt=0; } else mt=max(mt,getr(X[i],Y[i],mid)); if(mx>=len) r=ans=mid; else l=mid; } cout<<setprecision(10)<<fixed<<ans; }