using System;
using System.Linq;
using System.Collections.Generic;

namespace Contest
{
    class Program
    {
        static void Main(string[] args)
        {
            ABC115.C();
        }

        class ABC115
        {
            public static void A()
            {
                var D = Read.Int();
                switch (D)
                {
                    case 22: Console.WriteLine("Christmas Eve Eve Eve"); break;
                    case 23: Console.WriteLine("Christmas Eve Eve"); break;
                    case 24: Console.WriteLine("Christmas Eve"); break;
                    case 25: Console.WriteLine("Christmas"); break;
                }
            }
            public static void B()
            {
                var N = Read.Int();
                var P = Enumerable.Range(0, N).Select(i => Read.Int()).ToArray();
                Console.WriteLine(P.Sum() - P.Max() / 2);
            }
            public static void C()
            {
                var N = Read.Int();
                var K = Read.Int();
                var H = Enumerable.Range(0, N).Select(i => Read.Long()).ToArray();
                H = H.OrderBy(x => x).ToArray();
                long min = 1000000000;
                for(int i = 0; i <= N - K; ++i)
                {
                    var diff = H[i + K -1] - H[i];
                    min = Math.Min(min, diff);
                }
                Console.WriteLine(min);
            }
            public static void D()
            {
                var N = Read.Int();
                var X = Read.Long();
                var P = new long[N + 1];
                var B = new long[N + 1];
                P[0] = 1;
                for(int i = 0; i < N; ++i)
                {
                    P[i + 1] = P[i] * 2 + 1;
                    B[i + 1] = B[i] * 2 + 2;
                }
                Console.WriteLine(D_Count(N, X, P, B));
            }
            static long D_Count(int N, long X, long[] P, long[] B)
            {
                if (X == 0) { return 0; }
                if (X == 1) { return N == 0 ? 1 : 0; }
                var N1 = P[N - 1] + B[N - 1];
                if (X <= 1 +N1 ) { return D_Count(N - 1, X - 1, P, B); }
                if (X == N1 + 2) { return D_Count(N - 1, X - 2, P, B) + 1; }
                if (X <= N1 * 2 + 2) { return P[N - 1] + 1 + D_Count(N - 1, X - N1 - 2, P, B); }
                return P[N];
            }
        }
        class Util
        {
            public static Dictionary<long, int> Factorize(long x)
            {
                var dict = new Dictionary<long, int>();
                long minp = 2;
                while (x > 1)
                {
                    bool ok = false;
                    for (long p = minp; p * p <= x; ++p)
                    {
                        if (x % p == 0)
                        {
                            if (!dict.ContainsKey(p))
                            {
                                dict.Add(p, 0);
                            }
                            dict[p]++;
                            minp = p;
                            x /= p;
                            ok = true;
                            break;
                        }
                    }
                    if (!ok)
                    {
                        if (!dict.ContainsKey(x)) { dict.Add(x, 0); }
                        dict[x]++;
                        break;
                    }
                }
                return dict;
            }
        }

        static class Read
        {
            static Queue<string> queue = new Queue<string>();
            static void Enqueue() { var ss = Console.ReadLine().Split(' '); foreach (var s in ss) { queue.Enqueue(s); } }
            public static int Int() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt32(queue.Dequeue()); }
            public static long Long() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt64(queue.Dequeue()); }
            public static string Str() { if (queue.Count == 0) { Enqueue(); } return queue.Dequeue(); }
            public static int[] IntN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt32(s)).ToArray(); }
            public static long[] LongN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt64(s)).ToArray(); }
            public static string[] StrN() { return Console.ReadLine().Split(' '); }
            public static Tuple<int, int>[] TupleInt(int n) { List<Tuple<int, int>> list = new List<Tuple<int, int>>(); for (int i = 0; i < n; ++i) { var ab = Read.IntN(); list.Add(new Tuple<int, int>(ab[0], ab[1])); } return list.ToArray(); }
            public static Tuple<long, long>[] TupleLong(int n) { List<Tuple<long, long>> list = new List<Tuple<long, long>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<long, long>(ab[0], ab[1])); } return list.ToArray(); }
            public static Tuple<string, string>[] TupleStr(int n) { List<Tuple<string, string>> list = new List<Tuple<string, string>>(); for (int i = 0; i < n; ++i) { var ab = Read.StrN(); list.Add(new Tuple<string, string>(ab[0], ab[1])); } return list.ToArray(); }
            public static Tuple<double, double>[] TupleDouble(int n) { List<Tuple<double, double>> list = new List<Tuple<double, double>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<double, double>(ab[0], ab[1])); } return list.ToArray(); }
            public static long[,] LongMatrix(int r, int c)
            {
                var mat = new long[r, c];
                for (int i = 0; i < r; ++i)
                {
                    var x = Read.LongN();
                    for (int j = 0; j < c; ++j)
                    {
                        mat[i, j] = x[j];
                    }
                }
                return mat;
            }
            public static Dictionary<int, HashSet<int>> AdjacencyList(int N, int M)
            {
                Dictionary<int, HashSet<int>> dict = new Dictionary<int, HashSet<int>>();
                for (int i = 0; i <= N; ++i)
                {
                    dict.Add(i, new HashSet<int>());
                }
                for (int i = 0; i < M; ++i)
                {
                    var ab = Read.IntN();
                    dict[ab[0]].Add(ab[1]);
                    dict[ab[1]].Add(ab[0]);
                }
                return dict;
            }
        }
    }
}


Measured memory_bytes: 24784