using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (n, k) = (c[0], c[1]);
        var a = NList;
        Array.Sort(a);
        var d = new List<(int id, long val)>();
        for (var i = 0; i + 1 < n; ++i) d.Add((i, a[i + 1] - a[i]));
        d.Sort((l, r) => l.val.CompareTo(r.val));
        d = d.Take((int)(n - k)).ToList();
        d.Sort((l, r) => l.id.CompareTo(r.id));
        var ans = 0L;
        var min = a[0];
        var pos = 0;
        for (var i = 0; i < n; ++i)
        {
            if (pos >= d.Count || d[pos].id > i)
            {
                ans += a[i] - min;
                if (i + 1 < n) min = a[i + 1];
            }
            else ++pos;
        }
        WriteLine(ans);
    }
}