import java.io.*;
import java.util.*;

public class Main {
	FastScanner in = new FastScanner(System.in);
	PrintWriter out = new PrintWriter(System.out);


	long[][] pascalTriangleLong(int n) {
		long[][] res = new long[n+1][n+1];
		
		res[0][0] = 1;
		for (int i = 1; i <= n; i++) {
			for (int j = 0; j <= i; j++) {
				if (j < i) res[i][j] = (res[i][j] + res[i-1][j]);
				if (j > 0) res[i][j] = (res[i][j] + res[i-1][j-1]);
			}
		}
		
		return res;
	}
	
	double calcDist(double x1, double y1, double z1, double x2, double y2, double z2) {
		double dx = x1 - x2, dy = y1 - y2, dz = z1 - z2;
		return dx * dx + dy * dy + dz * dz;
	}
	
	double dfs(int at, int[] array, int idx) {
		array[at] = idx;
		if (at == m - 1) {
			double res = 0;
			for (int i = 0; i < m; i++) {
				for (int j = i + 1; j < m; j++) {
					int k = array[i], l = array[j];
					res += calcDist(L[k], a[k], b[k], L[l], a[l], b[l]);
				}
			}
			return res;
		}
		
		if (idx == n - 1) return 0;
	
		double res = 0;
		for (int i = idx + 1; i < n; i++) {
			res = Math.max(dfs(at + 1, array, i), res);
		}
		return res;
	}
	
	int n, m;
	double[] L, a, b;
	public void run() {
		n = in.nextInt();
		m = in.nextInt();
		L = new double[n];
		a = new double[n];
		b = new double[n];
		for (int i = 0; i < n; i++) {
			L[i] = in.nextDouble();
			a[i] = in.nextDouble();
			b[i] = in.nextDouble();
		}
		
		if (m == 0) {
			System.out.println(0);
			return;
		}
		
		double res = 0;
		for (int i = 0; i < n; i++) {
			res = Math.max(res, dfs(0, new int[m], i));
		}
		System.out.println(res);
		out.close();
	}

	public static void main(String[] args) {
		new Main().run();
	}

	public void mapDebug(int[][] a) {
		System.out.println("--------map display---------");

		for (int i = 0; i < a.length; i++) {
			for (int j = 0; j < a[i].length; j++) {
				System.out.printf("%3d ", a[i][j]);
			}
			System.out.println();
		}

		System.out.println("----------------------------");
		System.out.println();
	}

	public void debug(Object... obj) {
		System.out.println(Arrays.deepToString(obj));
	}

	class FastScanner {
		private InputStream stream;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public FastScanner(InputStream stream) {
			this.stream = stream;
			//stream = new FileInputStream(new File("dec.in"));

		}

		int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = stream.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		boolean isEndline(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}

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

		int[] nextIntArray(int n) {
			int[] array = new int[n];
			for (int i = 0; i < n; i++)
				array[i] = nextInt();

			return array;
		}

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

		long[] nextLongArray(int n) {
			long[] array = new long[n];
			for (int i = 0; i < n; i++)
				array[i] = nextLong();

			return array;
		}

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

		double[] nextDoubleArray(int n) {
			double[] array = new double[n];
			for (int i = 0; i < n; i++)
				array[i] = nextDouble();

			return array;
		}

		String next() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		String[] nextStringArray(int n) {
			String[] array = new String[n];
			for (int i = 0; i < n; i++)
				array[i] = next();

			return array;
		}

		String nextLine() {
			int c = read();
			while (isEndline(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndline(c));
			return res.toString();
		}
	}
}

Measured memory_bytes: 23164