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)

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

namespace SummerVacation
{
    class Program
    {
        static void Main(string[] args)
        {
            //List<List<int>> vs = new List<List<int>>() { new List<int> { 0, 10 }, new List<int> { 0, 5 } };

            //var num= vs.Where(g => g[0] == 0 && g[1] == g.Max()).Select(g => g.IndexOf(g.Max())).ToArray();

            //Console.WriteLine(num[0]);
            ////vs.RemoveAt(Convert.ToInt32(num));
            ////foreach (List<int> vs1 in vs)
            ////{
            ////    Console.WriteLine(string.Join("", vs1));

            ////}
            //Console.WriteLine("Hello World!");

            Console.ReadLine();
            string[] tmpstr=Regex.Split(Console.ReadLine(), @"\s+");
            int[] sep1_list = new int[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
            int[] sep2_list = new int[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};


            Hashtable ht1 = new Hashtable();
            Hashtable ht2 = new Hashtable();

            string tmp_string;

            for (int i = 0; i < tmpstr.Length; i += 2)
            {
                tmp_string = tmpstr[i];
                if (ht1.ContainsKey(tmp_string))
                {
                    ht1[tmp_string] = (int)ht1[tmp_string] + 1;
                }
                else
                {
                    ht1[tmp_string] = 1;
                }

                tmp_string = tmpstr[i+1];
                if (ht2.ContainsKey(tmp_string))
                {
                    ht2[tmp_string] = (int)ht2[tmp_string] + 1;
                }
                else
                {
                    ht2[tmp_string] = 1;
                }
            }


            while (true)
            {
                int Topnum = 0;
                string Indexnum = "";
                int tmpht1 = 0;

                foreach (DictionaryEntry x in ht1)
                {
                    if (Topnum < (int)x.Value)
                    {
                        tmpht1 = Topnum;
                        Topnum = (int)x.Value;
                        Indexnum = (string)x.Key;
                    }
                }


                int Topnum2 = 0;
                string Indexnum2 = "";
                int tmpht2 = 0;
                bool flag = true;

                foreach (DictionaryEntry x in ht2)
                {
                    if (Topnum2 < (int)x.Value)
                    {
                        tmpht2 = Topnum2;
                        Topnum2 = (int)x.Value;
                        Indexnum2 = (string)x.Key;
                    }
                }

                if (!(Indexnum == Indexnum2))
                {
                    Console.WriteLine(tmpstr.Length - Topnum - Topnum2);
                    break;
                }
                else
                {
                    if (ht1.Values.Count == 1 && ht2.Values.Count == 1)
                    {
                        Console.WriteLine(tmpstr.Length / 2);
                        break;
                    }
                    else if (Topnum > Topnum2)
                    {
                        if (Topnum2 == 1)
                        {
                            Console.WriteLine(tmpstr.Length / 2 - Topnum + Topnum2);
                            break;
                        }
                        else
                            flag = true;

                    }
                    else if(Topnum < Topnum2)
                    {
                        if (Topnum == 1)
                        {
                            Console.WriteLine(tmpstr.Length / 2 + Topnum - Topnum2);
                            break;
                        }
                        else
                            flag = false;

                    }
                    else
                    {
                        if (tmpht1 == 0)
                        {
                            flag = true;
                        }
                        else
                            flag = false;
                    }

                }
                if (flag)
                {
                    ht2.Remove(Indexnum2);
                }
                else
                    ht1.Remove(Indexnum);
            }
        }
    }
}