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;

public class MainClass
{
	public const long Giri = 1000000007;

	public static void Main(string[] args)
	{
		var n = Console.ReadLine().ToInt();
		var v = Input().ToInt();
		var l = new Dictionary<int, int>();
		var r = new Dictionary<int, int>();
		
		for(int i = 0; i < n; i++)
		{
			var d = r;
			if(i % 2 == 0)
			{
				d = l;
			}
			
			if(!d.ContainsKey(v[i]))
				d.Add(v[i], 0);
			d[v[i]]++;
		}
		
		var ls = l.OrderByDescending(k => k.Value).ToList();
		var rs = r.OrderByDescending(k => k.Value).ToList();
		var lskip = 0;
		var rskip = 0;
		if(ls[0].Key == rs[0].Key)
		{
			if(ls[0].Value > rs[0].Value)
			{
				if(rs.Count > 1)
					rskip = 1;
				else
					lskip = 1;
			}
			else
			{
				if(ls.Count > 1)
					lskip = 1;
				else
					rskip = 1;
			}
		}
		long wa = 0;
		int index = 0;
		foreach(var val in ls)
		{
			if(index != lskip)
				wa += val.Value;
			index++;
		}
		
		index = 0;
		foreach(var val in rs)
		{
			if(index != rskip)
				wa += val.Value;
			index++;
		}
		Console.WriteLine(wa);
	}
	
	static long GCD(long a, long b)
	{
		var v = new[] { a, b };
		while (v[1] != 0) { v = new[] { v[1], v[0] % v[1] }; }
		return v[0];
	}
	public static string[] Input() { return Console.ReadLine().Split(' '); }
	public static int Clamp(int val, int max, int min = 0) { return Math.Min(max, Math.Max(min, val)); }
}

public static class Smarter
{
	public static int ToInt(this string str) { return int.Parse(str); }
	public static long ToLong(this string str) { return long.Parse(str); }
	public static int[] ToInt(this string[] str)
	{
		var r = new int[str.Length];
		for(int i = 0; i < str.Length; i++) r[i] = str[i].ToInt();
		return r;
	 }
}