#include <bits/stdc++.h>
using namespace std;
// -------- Fast Scanner (fread) --------
struct FastScanner {
static const int BUFSIZE = 1 << 20;
int idx, size;
char buf[BUFSIZE];
FastScanner() : idx(0), size(0) {}
inline char read() {
if (idx >= size) {
size = (int)fread(buf, 1, BUFSIZE, stdin);
idx = 0;
if (size == 0) return 0;
}
return buf[idx++];
}
template <class T>
bool readInt(T &out) {
char c;
do {
c = read();
if (!c) return false;
} while (c <= ' ');
bool neg = false;
if (c == '-') { neg = true; c = read(); }
T val = 0;
while (c > ' ') {
val = val * 10 + (c - '0');
c = read();
}
out = neg ? -val : val;
return true;
}
};
static const long double EPS = 1e-12L;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
FastScanner fs;
int N;
long long L;
if (!fs.readInt(N)) return 0;
fs.readInt(L);
vector<long long> X(N), Y(N);
for (int i = 0; i < N; i++) {
fs.readInt(X[i]);
fs.readInt(Y[i]);
}
// intervals buffer reused each check to avoid realloc cost
vector<pair<long double, long double>> segs;
segs.reserve(N);
auto check = [&](long double R) -> bool {
segs.clear();
long double R2 = R * R;
for (int i = 0; i < N; i++) {
long double yi = (long double)Y[i];
long double ay = fabsl(yi);
if (ay > R + EPS) continue;
long double inside = R2 - yi * yi;
if (inside < 0) inside = 0; // guard for precision
long double dx = sqrtl(inside);
long double li = (long double)X[i] - dx;
long double ri = (long double)X[i] + dx;
if (ri <= 0.0L + EPS || li >= (long double)L - EPS) continue;
if (li < 0.0L) li = 0.0L;
if (ri > (long double)L) ri = (long double)L;
segs.emplace_back(li, ri);
}
if (segs.empty()) return false;
sort(segs.begin(), segs.end(),
[](const auto &a, const auto &b) {
if (a.first != b.first) return a.first < b.first;
return a.second > b.second;
});
long double cur = 0.0L;
for (auto &pr : segs) {
long double l = pr.first, r = pr.second;
if (l > cur + 1e-11L) return false; // gap
if (r > cur) cur = r;
if (cur >= (long double)L - 1e-11L) return true;
}
return cur >= (long double)L - 1e-11L;
};
// Binary search on R (real)
long double lo = 0.0L;
// Safe upper bound (coords up to ~1e9 usually; this is intentionally generous)
long double hi = 2.5e9L;
// Fixed iterations (avoid while(hi-lo) because of long double and speed)
for (int it = 0; it < 60; it++) {
long double mid = (lo + hi) / 2.0L;
if (check(mid)) hi = mid;
else lo = mid;
}
cout.setf(std::ios::fixed);
cout << setprecision(10) << (double)hi << "\n";
return 0;
}
