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;

class quiz
{
    public int solve(int n, int[] v)
    {
        int[] odd = new int[(int)n / 2];
        int[] even = new int[(int)n / 2];
        Dictionary<int, int> odic = new Dictionary<int, int>();
        Dictionary<int, int> edic = new Dictionary<int, int>();

        for (int i = 0; i < n / 2; i++)
        {
            even[i] = v[2 * i];
            odd[i] = v[2 * i + 1];
        }

        for (int i = 0; i < n / 2; i++)
        {
            edic[even[i]] = 0;
            odic[odd[i]] = 0;
        }

        for (int i = 0; i < n / 2; i++)
        {
            edic[even[i]]++;
            odic[odd[i]]++;
        }

        if (edic.Count == 1 && odic.Count == 1)
        {
            if (odd[0] != even[0])
                return 0;
            else
                return (int)n / 2;
        }

        var ne = edic.OrderBy(x => x.Value);
        var no = odic.OrderBy(x => x.Value);

        if (ne.ElementAt(0).Key != no.ElementAt(0).Key)
            return n - ne.ElementAt(0).Value - no.ElementAt(0).Value;

        if (ne.Count() == 1)
            return n - ne.ElementAt(0).Value - no.ElementAt(1).Value;

        if (no.Count() == 1)
            return n - ne.ElementAt(1).Value - no.ElementAt(0).Value;

        if (ne.ElementAt(0).Value == ne.ElementAt(1).Value)
            return n - ne.ElementAt(1).Value - no.ElementAt(0).Value;

        if (no.ElementAt(0).Value == no.ElementAt(1).Value)
            return n - ne.ElementAt(0).Value - no.ElementAt(1).Value;

        if (ne.ElementAt(0).Value >= no.ElementAt(0).Value)
            return n - ne.ElementAt(0).Value - no.ElementAt(1).Value;

        else
            return n - ne.ElementAt(1).Value - no.ElementAt(0).Value;

        return -1;
    }

    public int[] ParseIntBySpace(string str)
    {
        int[] array = new int[str.Length];
        int lastloc = 0, spaceloc = -1;

        for (int i = 0; i < str.Length; i++)
        {
            if (str[i] == ' ')
            {
                array[lastloc++] = int.Parse(str.Substring(spaceloc + 1, i - spaceloc - 1));
                spaceloc = i;
            }
            else if (i == str.Length - 1)
            {
                array[lastloc++] = int.Parse(str.Substring(spaceloc + 1, i - spaceloc));
            }
        }

        Array.Resize(ref array, lastloc);

        return array;
    }
}

class Example
{
    static void Main()
    {
        quiz ex = new quiz();

        //while (true)
        //{
        Console.WriteLine(ex.solve(int.Parse(Console.ReadLine()), ex.ParseIntBySpace(Console.ReadLine())));
        //}
    }
}