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 static Assistant.Input;
using static Assistant.Debug;
using System.Linq;
using Assistant;

namespace ABC111C
{
    class Program
    {
        static void Main(string[] args)
        {
            var N = ReadInt;

            var a = ReadInts;

            int[] count1 = new int[100001];
            int[] count2 = new int[100001];
            for (int i = 0; i < N; i++)
            {
                if (i % 2 == 0)
                {
                    count1[a[i]]++;
                }
                else
                {
                    count2[a[i]]++;
                }
            }

            int max1 = 0;
            int index1 = 0;
            int max2 = 0;
            int index2 = 0;
            for (int i = 0; i < 100001; i++)
            {
                if (count1[i] >= max1) { max1 = count1[i]; index1 = i; }
            }
            for (int i = 0; i < 100001; i++)
            {
                if (count2[i] >= max2) { max2 = count2[i]; index2 = i; }
            }

            int ans = 0;
            if (index1 != index2)
            {
                ans = N - max1 - max2;
            }
            else
            {
                if (max1 > max2)
                {
                    count2[index2] = 0;

                    max2 = 0;
                    index2 = 0;
                    for (int i = 0; i < 100001; i++)
                    {
                        if (count2[i] >= max2) { max2 = count2[i]; index2 = i; }
                    }
                    ans = N - max1 - max2;
                }
                else
                {
                    count1[index1] = 0;

                    max1 = 0;
                    index1 = 0;
                    for (int i = 0; i < 100001; i++)
                    {
                        if (count1[i] >= max1) { max1 = count1[i]; index1 = i; }
                    }
                    ans = N - max1 - max2;
                }

            }
            Console.WriteLine(ans);
        }


    }


}

namespace Assistant
{
    static class Input
    {
        static List<string> line = new List<string>();
        static int index = 0;
        static String ReadNext()
        {
            if (line.Count <= index) line.AddRange(Console.ReadLine().Split());
            return line[index++];
        }
        public static int ReadInt => int.Parse(ReadNext());
        public static long ReadLong => long.Parse(ReadNext());
        public static int[] ReadInts => Console.ReadLine().Split().Select(int.Parse).ToArray();
        public static long[] ReadLongs => Console.ReadLine().Split().Select(long.Parse).ToArray();
    }

    static class Debug
    {
        static public void Draw2D(int[,] map, int mode = 1)
        {
#if DEBUG
            int W = map.GetLength(0);
            int H = map.GetLength(1);

            int[,] map2 = new int[W + 1, H + 1];
            for (int i = 0; i < W + 1; i++)
            {
                for (int j = 0; j < H + 1; j++)
                {
                    if (i == 0 && j == 0) map2[i, j] = 0;
                    else if (i == 0) map2[i, j] = j - 1;
                    else if (j == 0) map2[i, j] = i - 1;
                    else map2[i, j] = map[i - 1, j - 1];
                }
            }

            for (int i = 0; i < W + 1; i++)
            {
                for (int j = 0; j < H + 1; j++)
                {
                    if (mode == 0) Console.Write(map2[i, j] % 10);
                    if (mode == 1) Console.Write(map2[i, j] + " ");
                }
                Console.WriteLine();
            }
            Console.WriteLine();
#endif
        }

        public static void Draw1D(int[] array, int mode = 0)
        {
#if DEBUG
            Console.WriteLine(string.Join(" ", array));
#endif
        }
    }
}