#include <bits/stdc++.h>
using namespace std;
using lli = long long;
void solve() {
int N, L;
cin >> N >> L;
vector <int> x(N), y(N);
for (int i = 0; i < N; ++i) {
cin >> x[i] >> y[i];
}
vector <int> ord(N);
iota(ord.begin(), ord.end(), 0);
sort(ord.begin(), ord.end(), [&](int i, int j) {
return x[i] < x[j];
});
auto possible = [&](double d) -> bool {
vector <pair <double, double>> range;
for (int i: ord) {
if (y[i] >= d) return true;
double p = y[i];
double delta = sqrt(d * d - p * p);
double l = (double) x[i] - delta, r = (double) x[i] + delta;
while (!range.empty() && range.back().second >= l) {
l = min(l, range.back().first);
r = max(r, range.back().second);
range.pop_back();
}
range.emplace_back(l, r);
}
for (auto [x, y]: range) {
if (x <= 0 && y <= L) return false;
}
return true;
};
double l = 0, r = L;
for (int iter = 0; iter < 64; ++iter) {
double mid = (l + r) / 2; //check if there exist a point which distance >= mid
if (possible(mid))
l = mid;
else
r = mid;
}
cout << setprecision(20) << fixed;
cout << l << '\n';
}
int main() {
std::cin.tie(0)->sync_with_stdio(0);
#ifdef LOCAL
auto begin = std::chrono::high_resolution_clock::now();
#endif
int tt = 1;
while (tt--) {
solve();
}
#ifdef LOCAL
auto end = std::chrono::high_resolution_clock::now();
auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
std::cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n";
#endif
return 0;
}
