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;

class quiz
{
    public int solve(int n, int[] v)
    {
        int[] odd = new int[100000 + 1];
        int[] even = new int[100000 + 1];
        int[] no = new int[100000 + 1];
        int[] ne = new int[100000 + 1];

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

        for (int i = 0; i < 100000 + 1; i++)
        {
            no[i] = i;
            ne[i] = i;
        }

        Array.Sort(odd, no);
        Array.Sort(even, ne);

        if (no[100000] != ne[100000])
            return n - odd[100000] - even[100000];
        if (odd[100000] + even[99999] >= odd[99999] + even[100000])
            return n - odd[100000] - even[99999];
        else
            return n - odd[99999] - even[100000];
    }

    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())));
        //}
    }
}