#include <algorithm>
#include <iostream>
#include <cstdio>
#include <map>
#include <numeric>
#include <cmath>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <complex>
#include <string.h>
#include <unordered_set>
#include <unordered_map>
using namespace std;

#define endl '\n'
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define uniq(v) (v).erase(unique((v).begin(), (v).end()), (v).end())

typedef long long ll;
typedef pair<int, int> P;
typedef unsigned int uint;
typedef unsigned long long ull;
struct pairhash {
public:
    template<typename T, typename U>
    size_t operator()(const pair<T, U> &x) const {
	size_t seed = hash<T>()(x.first);
	return hash<U>()(x.second) + 0x9e3779b9 + (seed<<6) + (seed>>2);
    }
};

const int inf = 1000000009;
const double eps = 1e-8;
int n, k;
int ns[10];
double res = 0;
int as[10];
set<vector<int> > memo;

void calc(int m, int rem, int bit, vector<int>& vec) {
    if (m == k) {
	double mini = inf, maxi = 0;
	for (int i = 0; i < k; i++) {
	    int count = 0;
	    double sum = 0;
	    for (int j = 0; j < n; j++) {
		if (as[j] == i) {
		    count++;
		    sum += ns[j];
		}
	    }
	    mini = min(mini, sum / count);
	    maxi = max(maxi, sum / count);
	}
	res = max(res, maxi - mini);
    } else if (m < k-1) {
	for (int i = 1; rem-i >= k-m-1; i++) {
	    //if (m == 0 && i == 2) printf("called\n");
	    int comb = (1 << i) - 1;
	    //if (m == 0 && i == 2) cout << comb << " " << bit << " " << memo.count(comb) << endl;
	    while (comb < 1 << n) {
		vector<int> t = vec;
		t.push_back(comb);
		sort(all(t));
		if ((comb & bit) == 0 && memo.count(t) == 0) {
		    for (int j = 0; j < n; j++) {
			if ((comb>>j)&1)
			    as[j] = m;
		    }
		    memo.insert(t);
		    calc(m+1, rem-i, bit | comb, t);
		}
		int x = comb & -comb, y = comb + x;
		comb = ((comb & ~y) / x >> 1) | y;
	    }
	}
    } else {
	for (int i = 0; i < n; i++) {
	    if (!((bit>>i)&1))
		as[i] = k-1;
	}
	calc(k, 0, 0, vec);
    }
}

int main() {
    scanf("%d%d", &n, &k);
    for (int i = 0; i < n; i++) {
	scanf("%d", &ns[i]);
    }
    vector<int> vec;
    calc(0, n, 0, vec);
    printf("%d\n", (int)ceil(res-eps));
}