题解 | #圆覆盖#

import java.io.*;
import java.util.*;
import java.math.BigInteger;

public class Main {
    static class Node {
        double x, y, v;

        Node(double x, double y, double v) {
            this.x = x;
            this.y = y;
            this.v = v;
        }
    }

    static void solve() {
        int n = in.nextInt();
        double m = in.nextDouble();
        Node[] a = new Node[n + 1];
        double s = 0;

        for (int i = 1; i <= n; i++) {
            double x = in.nextDouble();
            double y = in.nextDouble();
            double v = in.nextDouble();
            a[i] = new Node(x, y, v);
            s += v;
        }

        if (s < m) {
            out.println(-1);
            return;
        }

        double l = 0, r = 1e12; 
        while (Math.abs(r-l)>1e-6) {
            double mid = (l + r) / 2.0;
            long sum = 0;
            for (int i = 1; i <= n; i++) {
                double dis = a[i].x * a[i].x + a[i].y * a[i].y;
                if (dis <= mid * mid) {
                    sum += a[i].v;
                }
            }
            if (sum >= m) {
                r = mid;
            } else {
                l = mid;
            }
        }
        out.printf("%.10f\n", l);
    }

    public static void main(String[] args) {
        solve();
        out.flush();
    }

    static FastReader in = new FastReader();
    static PrintWriter out = new PrintWriter(System.out);

    static class FastReader {
        static BufferedReader br;
        static StringTokenizer st;

        FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            String str = "";
            while (st == null || !st.hasMoreElements()) {
                try {
                    str = br.readLine();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
                st = new StringTokenizer(str);
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }
    }
}