#include <bits/stdc++.h> #define ALL(x) x.begin(),x.end() using namespace std; typedef long long ll; typedef long double ld; ll n,L,con,a,b; int main(){ ios_base::sync_with_stdio(0); cin.tie(0);cout.tie(0); cin >> n >> L; vector<pair<ll,ll>> point; cin >> a >> b; b=abs(b); point.push_back({a,b}); for(int i=1;i<n;i++){ cin >> a >> b; b=abs(b); if(a==point.back().first){ point.back().second=min(point.back().second,b); }else{ point.push_back({a,b}); } } n=point.size(); ld l=0,r=1e9; while(abs(r-l)>=1e-4){ ld mid=(l+r)/2; ld last=0; for(int i=0;i<n;i++){ ld dist=sqrtl(mid*mid-(point[i].second*point[i].second)); if(point[i].first-dist<=last)last=max(last,point[i].first+dist); } if(last>=L)r=mid; else l=mid; } cout << fixed << setprecision(4) << l; }