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: Accepted)

#pragma warning disable

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.Serialization.Formatters.Binary;
using System.Text;
using System.Text.RegularExpressions;
using System.Diagnostics;
using System.Numerics;
using System.Collections;

static class MainClass
{
    public static void Main(string[] args)
    {
        
        var n = Console.ReadLine().ToInt32();
        var vn = Console.ReadLine().SplittedStringToInt32List();
        var count = 0;
        var vnodd = vn.Where(x => count++ % 2 == 0);
        count = 0;
        var vneven = vn.Where(x => count++ % 2 == 1);

        var odddic = new Dictionary<int, int>();
        var evendic = new Dictionary<int, int>();
        foreach (var item in vnodd)
        {
            if (odddic.ContainsKey(item))
                odddic[item]++;
            else
                odddic.Add(item, 1);
        }
        foreach (var item in vneven)
        {
            if (evendic.ContainsKey(item))
                evendic[item]++;
            else
                evendic.Add(item, 1);
        }
        var maxodds = odddic.OrderByDescending(x => x.Value).First();
        var maxevens = evendic.OrderByDescending(x => x.Value).First();
        if (maxodds.Key == maxevens.Key)
        {
            if (maxodds.Value > maxevens.Value)
            {
                try
                {
                    Console.WriteLine(n - maxodds.Value - evendic.OrderByDescending(x => x.Value).ToArray()[1].Value);
                }
                catch
                {
                    Console.WriteLine(n / 2);
                }
            }
            else if (maxodds.Value < maxevens.Value)
            {
                try
                {
                    Console.WriteLine(n - maxevens.Value - odddic.OrderByDescending(x => x.Value).ToArray()[1].Value);
                }
                catch
                {
                    Console.WriteLine(n / 2);
                }
            }
            else
            {
                try
                {
                    Console.WriteLine(n - maxevens.Value - Math.Max(odddic.OrderByDescending(x => x.Value).ToArray()[1].Value, evendic.OrderByDescending(x => x.Value).ToArray()[1].Value));
                }
                catch
                {
                    Console.WriteLine(n / 2);
                }
            }
        }
        else
        {
            Console.WriteLine(n - maxodds.Value - maxevens.Value);
        }
        Console.ReadLine();
    }

    public static int Manhattan(int x1,int x2,int y1,int y2)
    {
        return Math.Abs(x1 - x2) + Math.Abs(y1 - y2);
    }
    

    public static long Sums(IEnumerable<int> list)
    {
        var sum = 0l;
        foreach (var item in list)
        {
            sum += item;
        }
        return sum;
    }

    public static long f(long n,long b)
    {
        if (n < b)
        {
            return n;
        }
        else
        {
            return f((long)Math.Floor((double)n/b),b) + n % b;
        }
    }

    public static string N(long n,long b)
    {
        var sb = new StringBuilder();
        while (true)
        {
            sb.Append((n % b).ToString());
            n /= b;
            if (n < b)
            {
                sb.Append(n.ToString());
                break;
            }
        }
        return new string( sb.ToString().Reverse().ToArray() );
    }

    #region ライブラリ
    public static long ToInt64(this string str) => long.Parse(str);
    public static int ToInt32(this string str) => int.Parse(str);
    public static BigInteger ToBigInteger(this string str) => BigInteger.Parse(str);
    public static List<string> SplittedStringToList(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).ToList();
    public static List<int> SplittedStringToInt32List(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => int.Parse(x)).ToList();
    public static List<long> SplittedStringToInt64List(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => long.Parse(x)).ToList();
    public static List<BigInteger> SplittedStringToBigInteger(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => BigInteger.Parse(x)).ToList();
    public const int INF = int.MaxValue / 2;
    public const long LONGINF = long.MaxValue / 2;
    public const int Mod1e9 = 1000000007;

    public static void PrintArray(bool[,] array)
    {
        for (int i = 0; i < array.GetLength(0); i++)
        {
            var sb = new StringBuilder();
            for (int j = 0; j < array.GetLength(1); j++)
            {
                sb.Append(array[i, j]).Append(" ");
            }
            Console.WriteLine(sb.ToString());
        }
    }

    #endregion
}