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

namespace ProgrammingContest
{
    class MainClass : IDisposable
    {
        Scanner sc;
        Writer wr;
        string backPath = "..";
        char dirSep = System.IO.Path.DirectorySeparatorChar;
        string inFilePath = null;
        string outFilePath = null;
        public MainClass()
        {
            this.inFilePath = this.backPath
                            + this.dirSep
                            + this.backPath
                            + this.dirSep
                            + "in.txt";
            this.outFilePath = this.backPath
                             + this.dirSep
                             + this.backPath
                             + this.dirSep
                             + "out.txt";
        }
        static void Main(string[] args)
        {
            using (var mainClass = new MainClass())
            {
                //mainClass.MakeTestCase();
                mainClass.Solve();
            }
        }

        public void Dispose()
        {
            if (this.sc != null)
            {
                this.sc.Dispose();
                this.sc = null;
            }
            if (this.wr != null)
            {
                this.wr.Dispose();
                this.wr = null;
            }
        }

        void MakeTestCase()
        {
            Random rand = new Random();
            var res = new StringBuilder();



            using (var writer = new System.IO.StreamWriter(inFilePath))
                writer.Write(res.ToString());
        }

        void Solve()
        {
            this.wr = new Writer(this.isReactive);
            //this.wr = new Writer(this.outFilePath);
#if DEBUG
            if (!this.isReactive)
                this.sc = new Scanner(this.inFilePath);
            else
                this.sc = new Scanner();
#else
            this.sc = new Scanner();
#endif

            N = sc.NextInt;
            K = sc.NextInt;
            x = new int[N];
            y = new int[N];
            xs = new int[N];
            ys = new int[N];
            sum = new int[N + 2, N + 2];
            xDic = new Dictionary<int, int>();
            yDic = new Dictionary<int, int>();
            xDic2 = new Dictionary<int, int>();
            yDic2 = new Dictionary<int, int>();
            for (int i = 0; i < N; i++)
            {
                x[i] = sc.NextInt;
                y[i] = sc.NextInt;
                xs[i] = x[i];
                ys[i] = y[i];
            }
            Array.Sort(xs);
            Array.Sort(ys);
            for (int i = 0; i < N; i++)
            {
                xDic.Add(i, xs[i]);
                xDic2.Add(xs[i], i);
                yDic.Add(i, ys[i]);
                yDic2.Add(ys[i], i);
            }
            for (int i = 0; i < N; i++)
            {
                sum[xDic2[x[i]] + 1, yDic2[y[i]] + 1]++;
            }
            calc();
            long ans = (long)4e18 + 10;
            for (int x1 = 0; x1 < N; x1++)
            {
                for (int y1 = 0; y1 < N; y1++)
                {
                    for (int x2 = x1; x2 < N; x2++)
                    {
                        for (int y2 = y1; y2 < N; y2++)
                        {
                            if (Get(x1, y1, x2, y2) >= K)
                            {
                                ans = Math.Min(ans,  (long)Math.Abs(xDic[x1] - xDic[x2]) * Math.Abs(yDic[y1] - yDic[y2]));
                            }
                        }
                    }
                }
            }
            wr.WriteLine(ans);
        }

        Dictionary<int, int> xDic, yDic;
        Dictionary<int, int> xDic2, yDic2;
        int N, K;
        int[] x, y, xs, ys;
        int[,] sum;
        void calc()
        {
            for (int i = 0; i <= N + 1; i++)
            {
                for (int j = 0; j <= N; j++)
                {
                    sum[i, j + 1] += sum[i, j];
                }
            }
            for (int i = 0; i <= N; i++)
            {
                for (int j = 0; j <= N + 1; j++)
                {
                    sum[i + 1, j] += sum[i, j];
                }
            }
        }
        int Get(int x1, int y1, int x2, int y2)
        {
            return sum[x2 + 1, y2 + 1] - sum[x2 + 1, y1] - sum[x1, y2 + 1] + sum[x1, y1];
        }

        bool isReactive = false; // TODO: reactive check !!
    }

    class Writer : IDisposable
    {
        System.IO.TextWriter writer;
        StringBuilder sb;
        bool isReactive;
        public Writer(string path) : this(new System.IO.StreamWriter(path))
        {
        }
        public Writer(bool isReactive) : this(null, isReactive)
        {
        }
        public Writer(System.IO.TextWriter writer = null, bool isReactive = false)
        {
            this.writer = (writer ?? Console.Out);
            if (!(this.isReactive = isReactive))
            {
                this.sb = new StringBuilder();
            }
        }
        public void Dispose()
        {
            if (!isReactive)
                this.writer.Write(sb.ToString());
            if (!this.writer.Equals(Console.Out))
                this.writer.Dispose();
        }
        public void Write(object val)
        {
            if (this.isReactive)
            {
                this.writer.Write(val.ToString());
                this.writer.Flush();
            }
            else
                this.sb.Append(val.ToString());
        }
        public void Write(string format, params object[] vals)
        {
            if (this.isReactive)
            {
                this.writer.Write(format, vals);
                this.writer.Flush();
            }
            else
                this.sb.AppendFormat(format, vals);
        }
        public void WriteLine(object val)
        {
            this.Write(val.ToString() + System.Environment.NewLine);
        }
        public void WriteLine(string format, params object[] vals)
        {
            this.Write(format + System.Environment.NewLine, vals);
        }
    }

    class Scanner : IDisposable
    {
        Queue<string> buffer;
        char[] sep;
        System.IO.TextReader reader;
        public Scanner(string path) : this(new System.IO.StreamReader(path))
        {
        }
        public Scanner(System.IO.TextReader reader = null)
        {
            this.buffer = new Queue<string>();
            this.sep = new char[] { ' ' };
            this.reader = (reader ?? Console.In);
        }
        private void CheckBuffer()
        {
            if (this.buffer.Count == 0)
            {
                string str = null;
                while (string.IsNullOrEmpty(str))
                {
                    str = this.reader.ReadLine();
                }
                string[] sreArray = str.Split(this.sep);
                foreach (string elStr in sreArray)
                {
                    this.buffer.Enqueue(elStr);
                }
            }
        }

        public void Dispose()
        {
            if (!this.reader.Equals(Console.In))
                this.reader.Dispose();
        }

        public string Next
        {
            get
            {
                this.CheckBuffer();
                return this.buffer.Dequeue();
            }
        }

        public int NextInt
        {
            get
            {
                return int.Parse(this.Next);
            }
        }
        public double NextDouble
        {
            get
            {
                return double.Parse(this.Next);
            }
        }

        public long NextLong
        {
            get
            {
                return long.Parse(this.Next);
            }
        }
        public bool IsEmpty
        {
            get
            {
                this.CheckBuffer();
                return this.buffer.Count == 0;
            }
        }
    }
}


Measured memory_bytes: 13396