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;

namespace ARC103_C_hahahha
{
	internal class Program
	{
		public static void Main(string[] args)
		{
			int n = int.Parse(Console.ReadLine());
			string[] v = Console.ReadLine().Split(' ');
			List<int> vInts = new List<int>();

			bool diffrenceV = false;

			for (int i = 0; i < n; i++)
			{
				vInts.Add(int.Parse(v[i]));
			}

			int count = 0;
			for (int i = 0; i < n - 2; i++)
			{
				if (vInts[i] != vInts[i + 2])
				{
					vInts[i + 2] = vInts[i];
					count++;
					diffrenceV = true;
				}
			}

			if (diffrenceV)
			{
				Console.WriteLine(count);
			}
			else
			{
				Console.WriteLine(n / 2);
			}
		}
	}
}