#include <bits/stdc++.h>
#ifdef mlocal
#include "./Competitive-Code-Library/snippets/prettyprint.h"
#endif
using namespace std;
#define for_(i, s, e) for (int i = s; i < (int) e; i++)
#define for__(i, s, e) for (ll i = s; i < e; i++)
typedef long long ll;
typedef vector<int> vi;
typedef array<ll, 2> ii;
typedef pair<double, double> pdd;
#define endl '\n'
struct Line {
mutable ll k, m, p;
bool operator<(const Line &o) const { return k < o.k; }
bool operator<(ll x) const { return p < x; }
};
struct LineContainer : multiset<Line, less<>> {
// (for doubles, use inf = 1/.0, div(a,b) = a/b)
static const ll inf = LLONG_MAX;
ll div(ll a, ll b) { // floored division
return a / b - ((a ^ b) < 0 && a % b);
}
bool isect(iterator x, iterator y) {
if (y == end()) return x->p = inf, 0;
if (x->k == y->k) x->p = x->m > y->m ? inf : -inf;
else x->p = div(y->m - x->m, x->k - y->k);
return x->p >= y->p;
}
void add(ll k, ll m) {
auto z = insert({k, m, 0}), y = z++, x = y;
while (isect(y, z)) z = erase(z);
if (x != begin() && isect(--x, y)) isect(x, y = erase(y));
while ((y = x) != begin() && (--x)->p >= y->p)
isect(x, erase(y));
}
ll query(ll x) {
assert(!empty());
auto l = *lower_bound(x);
return l.k * x + l.m;
}
};
long double calc(Line &l, long double x) {
return x*x - (l.k * x + l.m);
}
int main() {
#ifdef mlocal
freopen("test.in", "r", stdin);
#endif
ios_base::sync_with_stdio(false);
cin.tie(0);
int n;
ll l;
cin >> n >> l;
vector <ii> pts(n);
for_(i, 0, n) cin >> pts[i][0] >> pts[i][1];
LineContainer lc;
for_(i, 0, n) {
lc.add(2 * pts[i][0], -pts[i][0] * pts[i][0] - pts[i][1] * pts[i][1]);
}
vector <Line> opt(lc.begin(), lc.end());
long double ans = -lc.query(0);
for_(i, 1, opt.size()) {
long double num = (opt[i - 1].m - opt[i].m), den = (opt[i].k - opt[i - 1].k);
long double intersect = num/den;
if (intersect < 0 or intersect > l) continue;
ans = max(ans, calc(opt[i-1], intersect));
// cout << setprecision(10) << (intersect*intersect + -(opt[i-1].k * intersect + opt[i-1].m)) << endl;
// cout << intersect << endl;
}
ans = max(ans, ((long double)l)*l - lc.query(l));
// cout << ans << endl;
cout << fixed << setprecision(8) << sqrtl(ans) << endl;
}
