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.Numerics;
class Program
{       
    
    public void Slove()
    {
        var n = int.Parse(Console.ReadLine());
        var array = Console.ReadLine().Split().Select(int.Parse).ToArray();
        var oddArray = 
            array.Where((x, i) => (i & 1) == 1).ToArray();
        var oddCount =
            oddArray
            .GroupBy(x => x)
            .OrderBy(x => x.Count())
            .ToArray();
        var evenArray = 
            array.Where((x, i) => (i & 1) == 0).ToArray();
        var evenCount =
            evenArray
            .GroupBy(x => x)
            .OrderBy(x => x.Count())
            .ToArray();
        //System.Console.WriteLine(oddCount);
        //System.Console.WriteLine(evenCount);
        if(evenCount.First().Key != oddCount.First().Key)
            System.Console.WriteLine(n - (oddCount.First().Count() + evenCount.First().Count()));
        else
        {
            System.Console.WriteLine(
                Math.Min(
                n - (oddCount.First().Count() + (evenCount.Skip(1).Any() ? evenCount.Skip(1).First().Count() : 0)),
                n - ((oddCount.Skip(1).Any() ? oddCount.Skip(1).First().Count() : 0) + evenCount.First().Count()))
                );
        }
    }
    
    static void Main(string[] args)
    {
        new Program().Slove();
    }
}