module main;

import std;

// 集合の分割を列挙する
T[][][] partition(T)(T[] arr, int k)
{
	T[][][] result;
	void backtrack(int start, int k, T[][] currentPartition)
	{
		if (k == 1) {
			result ~= currentPartition ~ [arr[start .. $]];
			return;
		}
		foreach (i; start .. arr.length.to!int - k + 1)
			backtrack(i + 1, k - 1, currentPartition ~ [arr[start .. i + 1]]);
	}
	backtrack(0, k, []);
	return result;
}

void main()
{
	// 入力
	auto N = readln.chomp.to!int;
	auto K = readln.chomp.to!int;
	double[] num;
	foreach (_; 0 .. N) {
		num ~= readln.chomp.to!double;
	}
	// 答えの計算
	double max = -1e10, min = 1e10;
	foreach (p; partition(num, K)) {
		foreach (e; p) {
			double m = e.mean;
			if (max < m)
				max = m;
			else if (min > m)
				min = m;
		}
	}
	// 答えの出力
	writeln(ceil(max - min));
}