#include <iostream>
#include <vector>
#include <algorithm>

#define LL  long long
#define REP(i, n) for(int i = 0;i < (int)(n);i++)
#define ALL(x) (x).begin(),(x).end()

using namespace std;

int main(void)
{
	int N,M;
	while(cin>>N>>M){
		vector<double> L(N);
		vector<double> a(N);
		vector<double> b(N);
		REP(i,N){
			cin>>L[i]>>a[i]>>b[i];
		}
		vector<int> perm(N,0);
		REP(i,M){
			perm[(int)perm.size()-1-i] = 1;
		}
		double res = 0;
		do{
			int size = 0;
			int index[20];
			REP(i,N)if(perm[i]==1)index[size++] = i;
			
			double tmp = 0;
			REP(ii,M)REP(jj,ii){
				int i = index[ii];
				int j = index[jj];
				tmp += (L[i]-L[j])*(L[i]-L[j])+(a[i]-a[j])*(a[i]-a[j])+(b[i]-b[j])*(b[i]-b[j]);
			}
			res = max(tmp,res);
		}
		while(next_permutation(ALL(perm)));
		printf("%.10f\n",res);
	}
	//LL num = 1;
	//for(int i = 20;i >= 10;i--)
	//{
	//	num *= i;
	//}
	//for(int j = 10;j >= 1;j--)
	//{
	//	num /= j;
	//}
	//cout << num << endl;
}