#include "bits/stdc++.h"
using namespace std;

typedef long long Int;
#define REP(i,n) for(int (i)=0;(i)<(int)(n);++(i))

int N, K;
int a[9];

int s[9];
int c[9];
double ans;

void rec(int d, int use) {
	if (d == N) {
		if (use == K) {
			double mi = 999999999;
			double ma = -1;
			for (int i = 0; i < use; i++) {
				double ave = (double)s[i] / c[i];
				mi = min(mi, ave);
				ma = max(ma, ave);
			}
			ans = max(ans, ma - mi);
		}
		return;
	}
	for (int i = 0; i <= use; i++) {
		s[i] += a[d];
		c[i]++;
		rec(d + 1, max(use, i + 1));
		s[i] -= a[d];
		c[i]--;
	}
}

int main() {
	cin >> N >> K;
	REP(i, N) cin >> a[i];
	ans = -1;
	rec(0,0);
	printf("%d\n", (int)ceil(ans));
}