#include <bits/stdc++.h> using namespace std; #define int double signed main() { ios::sync_with_stdio(false); cin.tie(nullptr); int n,L; cin >> n >> L; vector<pair<double,double>> a; int N=0; for (int i = 0; i < n; i++){ int x,y; cin >> x >> y; y=abs(y); if(i>0&&a[N-1].first==x) a[N-1].second=min(a[N-1].second,y); else{ N++; a.push_back({x,y}); } } int l=0,r=1e9; while(r-l>0.0003){ int mid=(l+r)/2; int rght=0; for (int i = 0; i < N; i++) { if(mid<a[i].second) continue; int pnt1=sqrt((mid*mid)-(a[i].second*a[i].second)); if(a[i].first-pnt1<=rght) rght=max(rght, pnt1+a[i].second); } if(rght>=L) { r=mid; }else{ l=mid; } } cout << setprecision(5) << fixed << (double)l << "\n"; return 0; }