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;

public class ABC_3
{
	static public void Main(string[] args)
	{
		int n = int.Parse(Console.ReadLine());
		string line = Console.ReadLine();

		char[] hoge = new char[n];
		int[] array = new int[n];
		int even = 0;
		int odd = 0;

		for(int i = 0; i < n; i++)
		{
			hoge[i] = line[i];
			array[i] = (int) char.GetNumericValue(hoge[i]);
		}

		for(int t = 0; t < n-2; t++)
		{
			if(t % 2 == 0) //even
			{
				if(array[t] == array[t + 2])
				{

				}
				else 
				{
					even++;
				}
			}
			else //odd
			{
				if(array[t] == array[t + 2])
				{

				}
				else
				{
					odd++;
				}
			}
		}

		if(even < odd)
		{
			Console.WriteLine(even);
		}
		else if(even > odd)
		{
			Console.WriteLine(odd);
		}
		else //even==odd
		{
			Console.WriteLine(even);
		}

		return;
	}
}