#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> indexed_set;
typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> indexed_multiset;
#define int long long
#define double long double
#define pb push_back
#define fastio ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define debug(x) cout << #x << " = " << x << '\n';
#define vdebug(a) cout << #a << " = "; for(auto x : a) cout << x << " "; cout << '\n';
const double eps = 1e-9;
const int mod = 1e9 + 7;
const int N = 2e5 + 5;
const int INF = 1e18;
signed main(){
fastio;
int n, l;
cin >> n >> l;
vector<pair<int, int>> v;
double lo = 0;
for(int i = 1; i <= n; i++){
int x, y;
cin >> x >> y;
v.pb({x, y});
lo = max(lo, (double)y);
}
double best = INF;
double hi = sqrtl(lo * lo + l * l);
while(hi - lo > 1e-4){
double mid = (hi + lo) / 2.0;
vector<pair<double, double>> lr; // l, r
for(int i = 0; i < n; i++){
int x = v[i].first;
int y = v[i].second;
// a*a + b*b = c*c
// a*a + y*y = mid*mid
double a = sqrtl(mid * mid - y * y);
lr.pb({x - a, x + a});
}
sort(lr.begin(), lr.end());
bool b = true;
if(lr[0].first > 0){
b = false;
}
double mxr = lr[0].second;
for(int i = 1; i < lr.size(); i++){
mxr = max(mxr, lr[i - 1].second);
if(lr[i].first > mxr){
b = false;
break;
}
}
if(b){
best = mid;
hi = mid;
}else{
lo = mid;
}
}
cout << best << '\n';
}
/*
freopen("x.in", "r", stdin);
freopen("x.out", "w", stdout);
*/
//atilla
