#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ll mask){return __builtin_ctzll(mask);}
int logOf(ll mask){return __lg(mask);}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T& container, string separator = " ", string finish = "\n"){
for(auto item: container) cout << item << separator;
cout << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
void solve(){
int n, L; cin >> n >> L;
vector<pair<ll, ll>> a(n);
for(int i = 0; i<n; ++i) cin >> a[i].first >> a[i].second;
for(int i = 0; i<n; ++i) a[i].second = abs(a[i].second);
sort(ALL(a));
double l = 0, r = 2e9;
for(int i = 0; i < 45; ++i) {
double mid = (l + r) / 2;
double ma = 0;
for(pair<ll, ll> j: a){
if (abs(j.second) > mid) continue;
double r = sqrt(mid * mid - j.second * j.second);
pair<double, double> cur = {j.first - r, j.first + r};
maximize(cur.first, 0); minimize(cur.second, L);
if (cur.first > cur.second) continue;
if (cur.first <= ma) maximize(ma, cur.second);
}
if (ma == L) r = mid;
else l = mid;
}
cout << fixed << setprecision(6) << l << "\n";
}
int main(void){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
clock_t start = clock();
solve();
cerr << "Time elapsed: " << clock() - start << "ms!\n";
return 0;
}
