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;
using System.Threading.Tasks;

namespace AtCorder
{
	public class Program
	{
		static void Main(string[] args)
		{
			long n = long.Parse(Console.ReadLine());
			List<long> v = Console.ReadLine().Split(' ').Select(long.Parse).ToList();
			long[] odd = new long[100001];
			long[] even = new long[100001];
			for (int i = 0; i < n; i+=2) {
				odd[v[i]]++;
				even[v[i + 1]]++;
			}

			var oo = odd.ToList();
			var ee = even.ToList();
			long maxo = oo.Max();
			long maxe = ee.Max();
			int indexo = oo.IndexOf(maxo);
			int indexe = ee.IndexOf(maxe);
			if (indexo == indexe) {
				oo.Sort();
				ee.Sort();
				if (oo[8] > ee[8]) {
					maxo = oo[8];
				} else {
					maxe = ee[8];
				}
			}

			long ans = n - maxo - maxe;
			Console.WriteLine(ans);
		}
	}
}