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


int main()
{
	int N, K;
	cin >> N >> K;
	vector<int> n( N );
	for( int i = 0; i < N; i++ ) {
		cin >> n[i];
	}

	int ans = 0;
	long long mn = pow( K, N );
	for( int mask = 0; mask < mn; mask++ ) {
		vector<int> sum( K );
		vector<int> num( K );
		long long m = mask;
		for( int i = 0; i < N; i++ ) {
			int k = m % K;
			m /= K;
			sum[k] += n[i];
			num[k]++;
		}
		int flag = 0;
		for( int i = 0; i < K; i++ ) if( num[i] == 0 ) flag = 1;
		if( flag ) continue;
		vector<double> ave( K );
		for( int i = 0; i < K; i++ ) ave[i] = (double)sum[i] / num[i];
		int a = ceil( *max_element( ave.begin(), ave.end() ) - *min_element( ave.begin(), ave.end() ) );
		ans = max( ans, a );
	}

	cout << ans << endl;
}