#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;++i)

using namespace std;
using R = long double;
const R EPS = 1e-9L; // [-1000,1000]->EPS=1e-8 [-10000,10000]->EPS=1e-7
inline int sgn(const R& r) {return (r > EPS) - (r < -EPS);}
inline R sq(R x) {return sqrt(max(x, 0.0L));}

// Description: ????????????
// Verifyed: various problem
const R INF = 1E40L;
const R PI = acos(-1.0L);
using P = complex<R>;
const P O = 0.0L;
using L = struct {P s, t;};
using VP = vector<P>;
using VL = vector<L>;
using C = struct {P c; R r;};

auto& operator >> (istream& is, P& p) { R x, y; is >> x >> y; p = P(x, y); return is;}
auto& operator << (ostream& os, P& p) { os << real(p) << " " << imag(p); return os;}

inline R dot(P o, P a, P b) {return real(conj(a - o) * (b - o));}
inline R det(P o, P a, P b) {return imag(conj(a - o) * (b - o));}
inline int sdot(P o, P a, P b) {return sgn(dot(o, a, b));}
inline int sdet(P o, P a, P b) {return sgn(det(o, a, b));}

//projection verify AOJ CGL_1_A
P proj(L l, P p) { R u = real((p - l.s) / (l.t - l.s)); return (1 - u) * l.s + u * l.t;}

// Circle // verified: AOJ 1183
enum RCC {OUT = 2, ON_OUT = 1, ISC = 0, ON_IN = -1, IN = -2};
int rcc(C a, C b) { R d = abs(a.c - b.c); return sgn(d - a.r - b.r) + sgn(d - abs(a.r - b.r));}

// cross point between circle and line
// verified: AOJ CGL_7_D
P cir(C c, R t) {return c.c + polar(c.r, t);}
VP cross(C c, L l) {
	P h = proj(l, c.c), e = polar(sq(norm(c.r) - norm(h - c.c)), arg(l.t - l.s));
	return VP{h - e, h + e};
}

// cross point between circles
// verified: AOJ CGL_7_E
VP cross(C a, C b) {
	P d = b.c - a.c, w = (norm(d) + norm(a.r) - norm(b.r)) / (2.0L * norm(d)) * d;
	return cross(a, {a.c + w, a.c + w + 1il * d});
}


int n, w;
P p[11];
int h[11];


inline R calc(R radius,R height){
	if (radius <= height) return radius;
	return sq(norm(radius) - norm(radius - height));
}

bool can(R radius) {
	
	R width = calc(radius,w);
	//cerr << fixed <<  "radius" << " " << radius  << " " << width << endl;
	if (sgn(width - 50.0) >= 0) return false;

	R lower = 0 + width, upper = 100 - width;


	VP cand;

	C c[11];
	rep(i, n)  c[i] = C{p[i], calc(radius,h[i])};

	rep(j, n)rep(i, j) if (abs(rcc(c[i], c[j])) <= 1) for (const auto &it : cross(c[i], c[j])) cand.push_back(it);

	VP corner;

	for (auto &y : {lower, upper})  for (auto &x : {lower, upper})corner.push_back(P(x, y));
	rep(i, 4) cand.push_back(corner[i]);
	swap(corner[2], corner[3]);

	L l[4];
	rep(i, 4) l[i]=L{corner[i], corner[(i + 1) % 4]};

	rep(i, n) rep(j, 4) if(sgn(abs(proj(l[j], c[i].c)-c[i].c) - c[i].r) < 0) for (const auto &it : cross(c[i], l[j])) cand.push_back(it);

	for (auto &p : cand) {
		if ( sgn(real(p)  - lower)  < 0 or sgn(imag(p)  - lower) < 0  or sgn(real(p) - upper)  > 0  or sgn(imag(p) - upper) > 0 ) continue;
		bool ok = true;
		rep(i, n) if ( sgn(abs(c[i].c - p) -c[i].r) < 0)  ok = false;
		if (ok) return true;
	}

	return false;
}


int main(void) {
	while (cin >> n >> w) {
		if (n == 0 and w == 0) break;

		rep(i, n) cin >> p[i] >> h[i];

		R low = 0.0, high = 150.0;

		
		rep(loop, 50) {
			const R mid = (low + high) / 2.0;
			if (can(mid))
				low = mid;
			else
				high = mid;
		}
		
		cout.precision(10);
		cout << fixed << low << endl;
	}
	return 0;
}

Measured memory_bytes: 3544