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

class Program
{
    static void Main(string[] args)
    {

        // 入力
        var n = int.Parse(Console.ReadLine());
        int[] v = Console.ReadLine().Split().Select(int.Parse).ToArray();

        //偶数奇数で登場回数の多い数字
        //int[] olist = new int[1000000];
        //int[] elist = new int[1000000];
        var olist = new Dictionary<int, int>() { };
        var elist = new Dictionary<int, int>() { };
        for (int i = 0; i < n; i++)
        {
            if (i % 2 == 0)
            {
                if (!olist.ContainsKey(v[i]))
                {
                    olist.Add(v[i], 1);
                }
                else
                {
                    olist[v[i]]++;
                }
            }
            else
            {
                if (!elist.ContainsKey(v[i]))
                {
                    elist.Add(v[i], 1);
                }
                else
                {
                    elist[v[i]]++;
                }
            }
        }

        var maxov = olist.OrderBy(val => val.Value).First().Value;
        var maxok = olist.OrderBy(val => val.Value).First().Key;
        var maxoc = olist.OrderBy(val => val.Value).Count();
        var maxev = elist.OrderBy(val => val.Value).First().Value;
        var maxek = elist.OrderBy(val => val.Value).First().Key;
        var maxec = elist.OrderBy(val => val.Value).Count();
        //数字が被っていないことを確認
        if (maxok == maxek)
        {
            if (maxoc == 1)
            {
                elist[maxek] = 0;
                maxev = elist.OrderBy(val => val.Value).First().Value;

            }
            else if (maxec == 1)
            {
                olist[maxok] = 0;
                maxov = olist.OrderBy(val => val.Value).First().Value;

            }
        }
        var ans = n - maxov - maxev;
        Console.WriteLine(ans);

    }
}