#include <bits/stdc++.h> using namespace std; #define ll long long void doing() { int n, L; cin >> n >> L; vector<pair<double, double> > v; for (int i = 0; i < n; i++) { int a, b; cin >> a >> b; v.emplace_back(a, b); } double l = 0, r = 1.5e9; while (r - l > 1e-3) { double mid = l + (r - l) / 2; double cur = 0; for (int i = 0; i < n; i++) { if (mid < v[i].second)continue; double d = sqrt(mid * mid - v[i].second * v[i].second); auto lx = v[i].first - d, rx = v[i].first + d; if (lx <= cur)cur = max(cur, rx); } if (cur >= L) r = mid; else l = mid; } cout << fixed << setprecision(6) << r << endl; } signed main() { ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr); #ifdef LOCAL freopen("IN.txt", "r", stdin); #else #endif int tc = 1; // cin >> tc; while (tc--) { doing(); } return 0; }