Problem:
Score : 300 points

Problem Statement

A sequence a_1,a_2,... ,a_n is said to be /\/\/\/ when the following conditions are satisfied:

For each i = 1,2,..., n-2, a_i = a_{i+2}.

Exactly two different numbers appear in the sequence.

You are given a sequence v_1,v_2,...,v_n whose length is even.
We would like to make this sequence /\/\/\/ by replacing some of its elements.
Find the minimum number of elements that needs to be replaced.

Constraints

2 \leq n \leq 10^5

n is even.

1 \leq v_i \leq 10^5

v_i is an integer.

Input

Input is given from Standard Input in the following format:

n
v_1 v_2 ... v_n

Output

Print the minimum number of elements that needs to be replaced.

Sample Input 1

4
3 1 3 2

Sample Output 1

1

The sequence 3,1,3,2 is not /\/\/\/, but we can make it /\/\/\/ by replacing one of its elements: for example, replace the fourth element to make it 3,1,3,1.

Sample Input 2

6
105 119 105 119 105 119

Sample Output 2

0

The sequence 105,119,105,119,105,119 is /\/\/\/.

Sample Input 3

4
1 1 1 1

Sample Output 3

2

The elements of the sequence 1,1,1,1 are all the same, so it is not /\/\/\/.

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

#if DEBUG
using System.Reflection;
using System.Threading.Tasks;
#endif

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Numerics;
using System.Globalization;

#if DEBUG
using System.Diagnostics;
#endif

namespace at103
{
    class Program
    {
        static string _inputFilename = "input.txt";
        static string _outputFilename = "output.txt";
        static bool _useFileInput = false;
        const string _delim = "!";


        static void Main(string[] args)
        {
            StreamWriter file = null;
#if DEBUG
            var testNumber = 0;
            var timer = new Stopwatch();
            foreach (var test in GetTests())
            {

                timer.Start();

                var defaultColor = Console.ForegroundColor;
                Console.ForegroundColor = ConsoleColor.DarkYellow;
                Console.WriteLine($"<!-- TEST #{testNumber} -->");
                Console.ForegroundColor = defaultColor;
                Console.SetIn(test);


#else
            if (_useFileInput)
            {
                Console.SetIn(File.OpenText(_inputFilename));
                file = new StreamWriter(_outputFilename);
                Console.SetOut(file);
            }
#endif

            try
            {
#if DEBUG
                Solution(testNumber);
#else
                Solution(0);
#endif
            }
            finally
            {
#if DEBUG
#else
                if (_useFileInput)
                {
                    file.Close();
                }
#endif
            }

#if DEBUG
                timer.Stop();

                Console.ForegroundColor = ConsoleColor.DarkYellow;
                Console.WriteLine($"<!-- TEST #{testNumber} FINISHED IN {timer.Elapsed.ToString(@"ss\:fff")}-->");
                Console.ForegroundColor = defaultColor;

                timer.Reset();
                testNumber++;
            }
#endif
        }



        static void Solution(int testNumber)
        {
            #region SOLUTION
            var n = ReadInt();
            var a = ReadIntArray();
            var max = 1000 * 100;
            var odd = new int[max + 1];
            var even = new int[max + 1];
            for (int i = 0; i < n; i++)
            {
                if (i % 2 == 0)
                {
                    odd[a[i]]++;
                }
                else
                {
                    even[a[i]]++;
                }
            }

            var on = new int[max + 1];
            var en = new int[max + 1];
            for (int i = 0; i < max + 1; i++)
            {
                on[i] = i;
                en[i] = i;
            }

            Array.Sort(odd, on);
            Array.Sort(even, en);
            if (on[max] != en[max])
            {
                Console.WriteLine(n - odd[max] - odd[max]);
            }
            else 
            {
                if (odd[max] + even[max - 1] > even[max] + odd[max - 1])
                {
                    Console.WriteLine(n - (odd[max] + even[max - 1]));
                }
                else
                {
                    Console.WriteLine(n - (even[max] + odd[max - 1]));
                }
            }

            //var maxOdd = 0;
            //var maxOdd2 = 0;
            //var on = -1;
            //var on2 = -1;

            //var maxEven = 0;
            //var maxEven2 = 0;
            //var en = -1;
            //var en2 = -1;

            //var oddStreak = 1;
            //var evenStreak = 1;
            //for (int i = 1; i < n / 2; i++)
            //{
            //    if (odd[i] == odd[i - 1])
            //    {
            //        oddStreak++;
            //    }
            //    else
            //    {
            //        oddStreak = 1;
            //        if (oddStreak >= maxOdd)
            //        {
            //            maxOdd2 = maxOdd;
            //            maxOdd = oddStreak;
            //            on2 = on;
            //            on = odd[i - 1];
            //        }
            //        else if (oddStreak > maxOdd2)
            //        {
            //            maxOdd2 = oddStreak;
            //        }
            //    }

            //    if (even[i] == even[i - 1])
            //    {
            //        evenStreak++;
            //    }
            //    else
            //    {
            //        evenStreak = 1;
            //        if (evenStreak >= maxEven)
            //        {
            //            maxEven2 = maxEven;
            //            maxEven = evenStreak;
            //        }
            //        else if (evenStreak > maxEven2)
            //        {
            //            maxEven2 = evenStreak;
            //        }
            //    }
            //}

            //if (oddStreak >= maxOdd)
            //{
            //    maxOdd2 = maxOdd;
            //    maxOdd = oddStreak;
            //}
            //else if (oddStreak > maxOdd2)
            //{
            //    maxOdd2 = oddStreak;
            //}

            //if (evenStreak >= maxEven)
            //{
            //    maxEven2 = maxEven;
            //    maxEven = evenStreak;
            //}
            //else if (evenStreak > maxEven2)
            //{
            //    maxEven2 = evenStreak;
            //}

            //Console.WriteLine(n - maxEven - maxOdd);
            //var n = readInt();
            //var m = readInt();

            //var a = readIntArray();
            //var b = readIntArray();
            #endregion
        }

        static int ReadInt()
        {
            return int.Parse(Console.ReadLine());
        }

        static long ReadLong()
        {
            return long.Parse(Console.ReadLine());
        }

        static int[] ReadIntArray()
        {
            return Console.ReadLine().Split(' ').Where(i => !string.IsNullOrEmpty(i)).Select(i => int.Parse(i)).ToArray();
        }

        static long[] ReadLongArray()
        {
            return Console.ReadLine().Split(' ').Where(i => !string.IsNullOrEmpty(i)).Select(i => long.Parse(i)).ToArray();
        }

#if DEBUG
        static IEnumerable<TextReader> GetTests()
        {
            var tests = new List<string>();
            var resName = Assembly.GetCallingAssembly().GetManifestResourceNames()[0];
            using (var resource = new StreamReader(Assembly.GetCallingAssembly().GetManifestResourceStream(resName)))
            {
                while (true)
                {
                    var nextText = new StringBuilder();
                    var endOfFile = false;
                    while (true)
                    {
                        var line = resource.ReadLine();

                        endOfFile = line == null;
                        if (endOfFile)
                        {
                            break;
                        }

                        if (line.Equals(_delim, StringComparison.Ordinal))
                        {
                            break;
                        }

                        nextText.AppendLine(line);
                    }

                    yield return new StringReader(nextText.ToString());

                    if (endOfFile)
                    {
                        break;
                    }
                }
            }
        }
#endif
    }
}