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.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace C
{
    public class Program
    {
        static void Main(string[] args)
        {
            var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            Console.SetOut(sw);
            Solve();
            Console.Out.Flush();
        }

        public static void Solve()
        {
            var n = int.Parse(Console.ReadLine());
            var vi = Console.ReadLine().Trim().Split(' ').Select(int.Parse).ToArray();
            var even = new Dictionary<int, int>();
            var odd = new Dictionary<int, int>();
            for (var i = 0; i < vi.Length; i++)
            {
                if (i % 2 == 0)
                {
                    if (even.ContainsKey(vi[i])) even[vi[i]]++;
                    else even.Add(vi[i], 1);
                }
                else
                {
                    if (odd.ContainsKey(vi[i])) odd[vi[i]]++;
                    else odd.Add(vi[i], 1);
                }
            }
            var evenOrder = even.Select(dict => new { X = dict.Key, Count = dict.Value }).OrderByDescending(x => x.Count).ToArray();
            var oddOrder = odd.Select(dict => new { X = dict.Key, Count = dict.Value }).OrderByDescending(x => x.Count).ToArray();

            var evenMax = evenOrder[0].Count;
            var oddMax = oddOrder[0].Count;
            if (evenOrder[0].X == oddOrder[0].X)
            {
                var tmpEven = evenOrder.Length > 1 ? evenOrder[1].Count : 0;
                var tmpOdd = oddOrder.Length > 1 ? oddOrder[1].Count : 0;
                if (tmpEven > tmpOdd) evenMax = tmpEven;
                else oddMax = tmpOdd;
            }

            var answer = vi.Length - evenMax - oddMax;
            Console.WriteLine(answer);
        }
    }
}