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)

using System;
using System.IO;
using System.Linq;
using System.Runtime;
using System.Reflection;
using System.Diagnostics;
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Text;
using System.Text.RegularExpressions;
using static System.Math;

class P
{
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        int[] v = Console.ReadLine().Split().Select(int.Parse).ToArray();
        Dictionary<int, int> d1 = new Dictionary<int, int>();
        Dictionary<int, int> d2 = new Dictionary<int, int>();
        List<int> v1 = new List<int>();
        List<int> v2 = new List<int>();
        for (int i = 0; i < v.Length; i++)
        {
            var d = i % 2 == 0 ? d1 : d2;
            if (!d.ContainsKey(v[i])) d.Add(v[i], 0);
            d[v[i]]++;
        }
        var sorted1 = d1.OrderByDescending(x => x.Value).ToList();
        var sorted2 = d2.OrderByDescending(x => x.Value).ToList();
        sorted1.Add(new KeyValuePair<int, int>(-1, 0));
        sorted2.Add(new KeyValuePair<int, int>(-1, 0));
        var count = sorted1[0].Value + sorted2[0].Value;
        if (sorted1[0].Key == sorted2[0].Key)
        {
            count = Max(sorted1[0].Value + sorted2[1].Value, sorted1[1].Value + sorted2[0].Value);
        }
        Console.WriteLine(n - count);
    }
}