using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Text;
using static System.Math;
using static Extensions;
using static MathExtensions;

public static class Program
{
    public static void Solve()
    {
        var (n, k) = (I, I);
        var a = Repeat(n, () => L).ToArray();
        Array.Sort(a);

        if (k == 1)
        {
            Console.WriteLine(a[a.Length - 1] - a[0]);
            Exit(0);
        }

        var d = Repeat(n - 1, i => (Value: a[i + 1] - a[i], Index: i)).ToArray();
        Array.Sort(d, (x, y) => y.Value.CompareTo(x.Value));
        Array.Resize(ref d, k - 1);
        Array.Sort(d, (x, y) => x.Value.CompareTo(y.Index));

        var ans = Repeat(k - 2, i => a[d[i + 1].Index] - a[d[i].Index + 1]).Sum();
        ans += a[d[0].Index] - a[0];
        ans += a[a.Length - 1] - a[d[d.Length - 1].Index + 1];

        Console.WriteLine(ans);
    }

    #region Scanners
    static Scanner _scanner;
    static char C => _scanner.NextChar();
    static string S => _scanner.NextString();
    static int I => _scanner.NextInt();
    static long L => _scanner.NextLong();
    static BigInteger B => _scanner.NextBigInteger();
    static double D => _scanner.NextDouble();
    static decimal M => _scanner.NextDecimal();
    #endregion

    public static void Main()
    {
        var sw = new StreamWriter(Console.OpenStandardOutput());
        sw.NewLine = "\n";
#if DEBUG
        sw.AutoFlush = true;
#else
        sw.AutoFlush = false;
#endif
        Console.SetOut(sw);
        _scanner = new Scanner(Console.OpenStandardInput());
        Solve();
        Console.Out.Flush();
    }
}

public static partial class Extensions
{
}

#region Library
public class Scanner
{
    private readonly Stream _stream;
    private const int _bufferSize = 1024;
    private readonly byte[] _buf = new byte[_bufferSize];
    private int _len, _ptr;

    public Scanner(Stream stream)
    {
        _stream = stream;
    }

    public byte ReadByte()
    {
        if (_ptr >= _len)
        {
            _len = _stream.Read(_buf, 0, _bufferSize);
            _ptr = 0;
        }
        return _buf[_ptr++];
    }

    public char ReadChar() => (char)ReadByte();

    public string ReadLine()
    {
        var r = new StringBuilder();
        if (_ptr == 0) r.Append(ReadChar());
        for (; _ptr < _len; _ptr++) r.Append((char)_buf[_ptr]);
        return r.ToString();
    }

    public char NextChar() => char.Parse(NextString());

    public string NextString()
    {
        var r = new StringBuilder();
        var b = ReadChar();
        while (b != ' ' && b != '\n')
        {
            r.Append(b);
            b = ReadChar();
        }
        return r.ToString();
    }

    public int NextInt() => (int)NextLong();

    public long NextLong()
    {
        var r = 0L;
        var b = ReadByte();
        var n = b == '-';
        if (n) b = ReadByte();
        while (b != ' ' && b != '\n')
        {
            r = r * 10 + b - '0';
            b = ReadByte();
        }
        return n ? -r : r;
    }

    public BigInteger NextBigInteger()
    {
        var r = new BigInteger();
        var b = ReadByte();
        var n = b == '-';
        if (n) b = ReadByte();
        while (b != ' ' && b != '\n')
        {
            r = r * 10 + b - '0';
            b = ReadByte();
        }
        return n ? -r : r;
    }

    public double NextDouble()
    {
        var i = 0L;
        var b = ReadByte();
        var n = b == '-';
        if (n) b = ReadByte();
        while (b != '.' && b != ' ' && b != '\n')
        {
            i = i * 10 + b - '0';
            b = ReadByte();
        }
        if (b != '.') return n ? -i : i;
        b = ReadByte();
        var f = 0L;
        var p = 0;
        while (b != ' ' && b != '\n')
        {
            f = f * 10 + b - '0';
            b = ReadByte();
            p++;
        }
        var r = i + (double)f / MathExtensions.Pow(10, p);
        return n ? -r : r;
    }

    public decimal NextDecimal() => decimal.Parse(NextString());

    public T Next<T>(Converter<string, T> parser) => parser(NextString());
}

[DebuggerStepThrough]
public static partial class Extensions
{
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void Assert(bool condition)
    {
        if (!condition) throw new Exception("Assertion failed");
    }

    public static string AsString(this IEnumerable<char> source) => new string(source.ToArray());

    public static void Exit(int exitCode)
    {
        Console.Out.Flush();
        Environment.Exit(exitCode);
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void ForEach<T>(this IEnumerable<T> source, Action<T> action)
    {
        foreach (var item in source) action(item);
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void ForEach<T, _>(this IEnumerable<T> source, Func<T, _> func)
    {
        foreach (var item in source) func(item);
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void ForEach<T>(this IEnumerable<T> source, Action<T, int> action)
    {
        var i = 0;
        foreach (var item in source) action(item, i++);
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void ForEach<T, _>(this IEnumerable<T> source, Func<T, int, _> func)
    {
        var i = 0;
        foreach (var item in source) func(item, i++);
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void Repeat(int count, Action action)
    {
        for (var i = 0; i < count; i++) action();
    }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void Repeat(int count, Action<int> action)
    {
        for (var i = 0; i < count; i++) action(i);
    }

    public static IEnumerable<T> Repeat<T>(Func<T> func)
    {
        for (var i = 0; ; i++) yield return func();
    }

    public static IEnumerable<T> Repeat<T>(int count, Func<T> func)
    {
        for (var i = 0; i < count; i++) yield return func();
    }

    public static IEnumerable<T> Repeat<T>(Func<int, T> func)
    {
        for (var i = 0; ; i++) yield return func(i);
    }

    public static IEnumerable<T> Repeat<T>(int count, Func<int, T> func)
    {
        for (var i = 0; i < count; i++) yield return func(i);
    }

    public static void Swap<T>(ref T x, ref T y)
    {
        var tmp = x; x = y; y = tmp;
    }

    public static (T1[], T2[]) Unzip<T1, T2>(this ICollection<(T1, T2)> source)
    {
        var ts1 = new T1[source.Count];
        var ts2 = new T2[source.Count];
        var i = 0;
        foreach (var (t1, t2) in source) { ts1[i] = t1; ts2[i] = t2; i++; }
        return (ts1, ts2);
    }

    public static (T1[], T2[], T3[]) Unzip<T1, T2, T3>(this ICollection<(T1, T2, T3)> source)
    {
        var ts1 = new T1[source.Count];
        var ts2 = new T2[source.Count];
        var ts3 = new T3[source.Count];
        var i = 0;
        foreach (var (t1, t2, t3) in source) { ts1[i] = t1; ts2[i] = t2; ts3[i] = t3; i++; }
        return (ts1, ts2, ts3);
    }

    public static (T1[], T2[], T3[], T4[]) Unzip<T1, T2, T3, T4>(this ICollection<(T1, T2, T3, T4)> source)
    {
        var ts1 = new T1[source.Count];
        var ts2 = new T2[source.Count];
        var ts3 = new T3[source.Count];
        var ts4 = new T4[source.Count];
        var i = 0;
        foreach (var (t1, t2, t3, t4) in source) { ts1[i] = t1; ts2[i] = t2; ts3[i] = t3; ts4[i] = t4; i++; }
        return (ts1, ts2, ts3, ts4);
    }

    public static IEnumerable<T> Zip<T1, T2, T3, T>(this IEnumerable<T1> first, IEnumerable<T2> second, IEnumerable<T3> thrid, Func<T1, T2, T3, T> resultSelector)
    {
        using (var e1 = first.GetEnumerator())
        using (var e2 = second.GetEnumerator())
        using (var e3 = thrid.GetEnumerator())
        {
            while (e1.MoveNext() && e2.MoveNext() && e3.MoveNext())
                yield return resultSelector(e1.Current, e2.Current, e3.Current);
        }
    }

    public static IEnumerable<T> Zip<T1, T2, T3, T4, T>(this IEnumerable<T1> first, IEnumerable<T2> second, IEnumerable<T3> thrid, IEnumerable<T4> fourth, Func<T1, T2, T3, T4, T> resultSelector)
    {
        using (var e1 = first.GetEnumerator())
        using (var e2 = second.GetEnumerator())
        using (var e3 = thrid.GetEnumerator())
        using (var e4 = fourth.GetEnumerator())
        {
            while (e1.MoveNext() && e2.MoveNext() && e3.MoveNext() && e4.MoveNext())
                yield return resultSelector(e1.Current, e2.Current, e3.Current, e4.Current);
        }
    }
}

[DebuggerStepThrough]
public static class MathExtensions
{
    public static int Gcd(int left, int right)
    {
        int r;
        while ((r = left % right) != 0) { left = right; right = r; }
        return right;
    }

    public static long Gcd(long left, long right)
    {
        long r;
        while ((r = left % right) != 0L) { left = right; right = r; }
        return right;
    }

    public static BigInteger Gcd(BigInteger left, BigInteger right)
        => BigInteger.GreatestCommonDivisor(left, right);

    public static int HighestOneBit(int x)
    {
        x |= x >> 01;
        x |= x >> 02;
        x |= x >> 04;
        x |= x >> 08;
        x |= x >> 16;
        return x - (x >> 1);
    }

    public static long HighestOneBit(long x)
    {
        x |= x >> 01;
        x |= x >> 02;
        x |= x >> 04;
        x |= x >> 08;
        x |= x >> 16;
        x |= x >> 32;
        return x - (x >> 1);
    }

    public static int Lcm(int left, int right) => left / Gcd(left, right) * right;

    public static long Lcm(long left, long right) => left / Gcd(left, right) * right;

    public static BigInteger Lcm(BigInteger left, BigInteger right)
        => left / Gcd(left, right) * right;

    public static int Pow(int value, int exponent)
    {
        var r = 1;
        while (exponent > 0)
        {
            if ((exponent & 1) == 1) r *= value;
            value *= value;
            exponent >>= 1;
        }
        return r;
    }

    public static long Pow(long value, int exponent)
    {
        var r = 1L;
        while (exponent > 0)
        {
            if ((exponent & 1) == 1) r *= value;
            value *= value;
            exponent >>= 1;
        }
        return r;
    }

    public static long Fact(int value)
    {
        var r = 1L;
        for (var i = 2; i <= value; i++) r *= i;
        return r;
    }
}
#endregion