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 static System.Console;
using System.Collections.Generic;
using System.Linq;

namespace Atcoder
{
    class Program
    {
        static void Main(string[] args)
        {
            var n = InputNum();
            var a = InputNumList();

            var even = Enumerable.Repeat(0, 100010).ToList();
            var odd = Enumerable.Repeat(0, 100010).ToList();

            for (int i = 0; i < n; i++)
            {
                if (i % 2 == 0) even[a[i]]++;
                else odd[a[i]]++;
            }

            //int evenMax = 0;
            //int evenNext = 0;
            //for (int i = 1; i < even.Count; i++)
            //{
            //    if(even[i] > even[evenMax])
            //    {
            //        evenNext = evenMax;
            //        evenMax = i;
            //    }
            //    else if (even[i] > even[evenNext])
            //    {
            //        evenNext = i;
            //    }
            //}

            int evenMaxCount = even.Max();
            int evenMaxNum = even.IndexOf(evenMaxCount);
            int evenNextMaxCount = even.Where(x => x != evenMaxCount).Max();
            int evenNextMaxNum = even.IndexOf(evenNextMaxCount);

            int oddMaxCount = odd.Max();
            int oddMaxNum = odd.IndexOf(oddMaxCount);
            int oddNextMaxCount = odd.Where(x => x != oddMaxCount).Max();
            int oddNextMaxNum = odd.IndexOf(oddNextMaxCount);

            int ans = 0;
            if (evenMaxNum != oddMaxNum)
            {
                ans = n - evenMaxCount - oddMaxCount;
            }
            else
            {
                ans = n - Math.Max(evenMaxCount + oddNextMaxCount, oddMaxCount + evenNextMaxCount);
            }
            WriteLine(ans);
        }

        static int InputNum()
        {
            return int.Parse(ReadLine());
        }
        static List<int> InputNumList()
        {
            return ReadLine().Split(' ').Select(int.Parse).ToList();
        }
    }
}