//#pragma GCC optimize("Ofast,unroll-loops,O3")
//#pragma GCC target("avx,avx2,sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,fma,tune=native")
#include<bits/stdc++.h>
//#include<bits/extc++.h>
//#pragma pack(1)
#define fast ios::sync_with_stdio(0); cin.tie(0);
#define int long long
#define double long double
#define pii pair<int,int>
#define x first
#define y second
#define N 1000015
using namespace std;
//using namespace __gnu_pbds;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//typedef tree<int, null_type,less_equal<int>, rb_tree_tag,tree_order_statistics_node_update> order_multiset;
//typedef tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> order_set;
int n,L;
pii arr[N];
map<int,int>mp;
bool check(double val){
//cout<<sqrt(val)<<" -> \n";
double l=0,r=-1;
for (int i=1;i<=n;i++){
if (val*val-arr[i].y*arr[i].y<=0.000001) continue;
double dl=(double)arr[i].x-sqrt(val*val-arr[i].y*arr[i].y);
double dr=(double)arr[i].x+sqrt(val*val-arr[i].y*arr[i].y);
if (l<r){
if (dl-r>0.000001){
l=dl;
}
else {
r=max(r,dr);
l=min(l,dl);
}
}
else {
if (r-dl>0.000001){
r=dr;
l=dl;
}
}
// cout<<l<<" "<<r<<'\n';
}
if (r>=L){
// cout<<"OK\n";
return 1;
}
// cout<<"NO\n";
return 0;
}
bool cmp(pii a,pii b){
if (a.x!=b.x) return a.x<b.x;
else return a.y>b.y;
}
signed main(){
fast
// freopen("loan.in","r",stdin);
// freopen("loan.out","w",stdout);
cout<<fixed<<setprecision(5);
cin>>n>>L;
for (int i=1;i<=n;i++){
cin>>arr[i].x>>arr[i].y;
if (!mp[arr[i].x]) mp[arr[i].x]=arr[i].y;
else mp[arr[i].x]=min(arr[i].y,mp[arr[i].x]);
}
n=0;
for (auto i:mp) arr[++n]=i;
double l=0,r=4e18;
while (r-l>0.00001){
double mid=(l+r)/2.0;
// cout<<l<<" ~ "<<r<<'\n';
if (check(mid)) r=mid;
else l=mid;
}
cout<<(double)(l)<<'\n';
}
