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

using namespace std;

bool f0(vector<int>& a, int m,int k) {
	int s = 0;
	for (int i=0,j=0; i< a.size(); i++) {
		while (a[i]- a[j]> m) j++;
		s+= i-j;
	}
	return s >= k;
}

int f(vector<int>& a,int k) {
	sort(a.begin(), a.end());

	int g = 0;
	int h = a.back()- a[0];
	while (g <h) {
		int m=g+(h-g)/2;
		if(f0(a,m,k)) {
			h=m;
		} else {
			g=m+1;
		}
	}

	return g;
}

int main() {
	int n, k;
	cin >> n>> k;
	vector<int> a(n,0);
	for (int i=0; i<n; i++) {
		cin >>a[i];
	}
	cout << f(a,k) << endl;
	return 0;
}