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# (.NET Core 3.1.201) (judge verdict: Accepted)

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

class MainClass
{
    static void Main()
    {
        int n = int.Parse(ReadLine());
        var v = ReadLine().Split().Select(int.Parse).ToArray();

        var dic1 = new Dictionary<int, int>();
        var dic2 = new Dictionary<int, int>();
        for (int i = 0; i < n; i+=2)
        {
            if (dic1.ContainsKey(v[i])) dic1[v[i]]++;
            else dic1[v[i]] = 1;
        }
        for (int i = 1; i < n; i+=2)
        {
            if (dic2.ContainsKey(v[i])) dic2[v[i]]++;
            else dic2[v[i]] = 1;
        }
        var pair1 = dic1.OrderByDescending(_ => _.Value).ToArray();
        var pair2 = dic2.OrderByDescending(_ => _.Value).ToArray();
        var odd = pair1[0].Value;
        var even = pair2[0].Value;
        var minus = 0;
        if (pair1[0].Key == pair2[0].Key)
        {
            if (pair1.Length >= 2)
            {
                minus = odd - pair1[1].Value;
            }
            else
            {
                minus = odd;
            }
            if (pair2.Length >= 2)
            {
                minus = Min(minus, even - pair2[1].Value);
            }
            else
            {
                minus = Min(minus, even);
            }
        }
        WriteLine(n-odd-even+minus);
    }
}