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;

class Program
{
    static void Main(string[] args)
    {
        int n = int.Parse(System.Console.ReadLine().Trim());
        int[] line = Array.ConvertAll(System.Console.ReadLine().Trim().Split(' '),int.Parse);

        Dictionary<int, int> s = new Dictionary<int, int>();
        Dictionary<int, int> t = new Dictionary<int, int>();
        Dictionary<int, int> tmp;

        for (int i = 0; i < n ; i++)
        {
           
            tmp = (i % 2 == 0) ? s: t;

            if(tmp.ContainsKey(line[i]))
            {
                tmp[line[i]]++;
            }
            else
            {
                tmp.Add(line[i], 1);
            }
        }

        if (s.Count == 1 && t.Count == 1 && s.First().Key != t.First().Key)
        {
            System.Console.WriteLine("{0}",0);
            return;
        }
        else if(s.Count == 1 && t.Count == 1)
        {
            System.Console.WriteLine("{0}", s.First().Value);
            return;
        }

        int s1 = 0, s2 = 0, t1 = 0, t2 = 0;

        s = s.OrderByDescending(x => x.Value).ToDictionary(x => x.Key, x => x.Value);
        t = t.OrderByDescending(x => x.Value).ToDictionary(x => x.Key, x => x.Value);

        s1 = s[s.Keys.ToList()[0]];
        t1 = t[t.Keys.ToList()[0]];

        if (s.Count > 1) s2 = s[s.Keys.ToList()[1]];
        if (t.Count > 1) t2 = t[t.Keys.ToList()[1]];

        //sを最頻値で、tを二番目で書き換え
        //tを最頻値で、sを二番目で書き換え
        int sRlt = (n / 2 - s1) + (n / 2 - t2);
        int tRlt = (n / 2 - s2) + (n / 2 - t1);

        System.Console.WriteLine("{0}", Math.Min(sRlt,tRlt));

    }

    


}