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: Runtime Error)

using System;
using System.Collections.Generic;
using System.Linq;

namespace C
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] V = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
            var D0 = new Dictionary<int, int>();
            var D1 = new Dictionary<int, int>();
            for(int i = 0; i < n; i += 2)
            {
                if (D0.ContainsKey(V[i])) D0[V[i]]++;
                else D0[V[i]] = 1;
            }
            for (int i = 1; i < n; i += 2)
            {
                if (D1.ContainsKey(V[i])) D1[V[i]]++;
                else D1[V[i]] = 1;
            }
            var S0 = D0.OrderBy(x => x.Value);
            var S1 = D1.OrderBy(x => x.Value);
            //最頻値の配列
            var x= S0.Take(1).ToArray();
            var s0maxV = x[0];
            var F0 = S0.Where(x=>x.Value==s0maxV.Value).ToArray();
            
            var y = S1.Take(1).ToArray();
            var s1maxV = y[0];
            var F1 = S1.Where(x => x.Value == s1maxV.Value).ToArray();

            bool chk = true;//すべて一致するときtrue
            if (F0.Length != F1.Length) chk = false;
            else
            {
                for (int i = 0; i < F0.Length; i++)
                {
                    if (F0[i].Key != F1[i].Key) chk = false;
                }
            }
            
            if(chk)
            {
                int z = F0.Length;
                if (x.Length == z)
                {
                    Console.WriteLine(n/2);
                }
                else
                {
                    var a0 = S0.Take(z+1).ToArray();
                    var a1 = S1.Take(z+1).ToArray();
                    if (a0[z].Value > a1[z].Value)
                    {
                        Console.WriteLine(n - a0[z].Value - a1[0].Value);
                    }
                    else
                    {
                        Console.WriteLine(n - a1[0].Value - a0[z].Value);
                    }
                }
            }
            else
            {
                Console.WriteLine(n - x[0].Value - y[0].Value);
            }
        }
    }
}