#include <bits/stdc++.h> using namespace std; #define ll long long void doing() { int n; long double L; cin >> n >> L; vector<pair<long double, long double>> v; for (int i = 0; i < n; i++) { int a, b; cin >> a >> b; v.emplace_back(a, b); } auto cal = [&](long double x, long double y, long double r)-> pair<double, double> { auto cur = sqrt(r * r - y * y); return {x - cur, x + cur}; }; auto check = [&](long double x) { double lx = 0; for (int i = 0; i < v.size(); i++) { if (v[i].second > x)continue; auto [l, r] = cal(v[i].first, v[i].second, x); if (l <= lx)lx = max(lx, r); } return lx >= L; }; long double l = 0, r = 1.5e9; while (r - l >= 1e-3) { double mid = l + (r - l) / 2; if (check(mid)) r = mid; else l = mid; } cout << fixed << setprecision(4) << 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; }