题解 | #小红的中位数查询（easy）#

import java.util.Scanner;

import java.lang.Math;

import java.util.Arrays;

public class Main{

public static void main(String[] args){
    double[] x = new double[1000010];
    double[] y = new double[1000010];
    double[] r = new double[1000010];
    
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    double[] s = new double[n];
    int k = sc.nextInt();
    for(int i = 0;i < n;i++){
        x[i] = sc.nextInt();
        y[i] = sc.nextInt();
        r[i] = sc.nextInt();
        s[i] = Math.PI * r[i] * r[i];
        s[i] = s[i] * Math.max(0, r[i] - Math.sqrt(x[i] *x[i] + y[i] * y[i]));
        
    }
    
    Arrays.sort(s);
    double sum = 0;
    for(int i = 0;i < n - k;i++){
        sum += s[i];
    }
    System.out.println(sum);
}

}