#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;
// #pragma GCC target ("avx2")
// #pragma GCC optimize ("O3")
// #pragma GCC optimize ("unroll-loops")
// #pragma GCC optimize("fast-math")
#define ll long long
#define ld long double
#define vi vector<ll>
#define endl "\n"
#define pr pair<ll, ll>
#define ff first
#define ss second
#define all(x) x.begin(), x.end()
const int mod = 1e9+7;
void _p(ll a){cout<<a<<endl;}
void _p(string a){cout<<a<<endl;}
void _p(ld a) {cout<<a<<endl;}
template <class T>
void _p(vector<T> a){for(T val:a)cout<<val<<" ";cout<<endl;}
#define debug(x) cout<<#x<<" -> ";_p(x)
typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update > ordered_set;
vector<pr> move8 = {{1, 0}, {1, 1}, {0, 1}, {-1, 1}, {-1, 0}, {-1, -1}, {0, -1}, {1, -1}};
vector<pr> move4 = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
vector<pr> move2 = {{0, 1}, {1, 0}};
void solution();
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.precision(10);
solution();
return 0;
}
void solution() {
ll N; cin >> N;
ld L; cin >> L;
vector<pair<ld, ld>> a(N);
for (int i = 0; i < N; i++) {
ld x, y; cin >> x >> y;
a[i] = {x, y};
}
auto isValid = [&](ld d) {
vector<pair<ld, ld>> cords(N);
for (int i = 0; i < N; i++) {
if (d < a[i].ss) continue;
ld p = max(a[i].ff - sqrt(abs(d*d - a[i].ss*a[i].ss)), (ld)0);
ld q = min(a[i].ff + sqrt(abs(d*d - a[i].ss*a[i].ss)), L);
cords[i] = {p, q};
}
sort(all(cords));
ld z = cords[0].ff;
if (z > 0 ) return true;
for (auto [x, y] : cords) {
if (z >= x) z = max(z, y);
else return true;
}
return z < L;
};
ld p = 0, q = 1e9+1;
ld ans = 0;
while (q-p > 1e-6) {
ld mid = (p + q)/2;
if (isValid(mid)) {
ans = mid;
p = mid;
} else q = mid;
}
cout << ans << endl;
}
