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;

namespace AtCoder
{
    internal static class Program
    {
        private static void Main()
        {
            int n = int.Parse(Console.ReadLine());
            int[] nbrs = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);

            int res = 0;
            int nbr1 = Counter(nbrs, 0, n);
            int nbr2 = Counter(nbrs, 1, n, nbr1);

            for (int i = 0; i < n; i += 2)
            {
                if (nbrs[i] != nbr1)
                    res++;
            }

            for (int i = 1; i < n; i += 2)
            {
                if (nbrs[i] != nbr2)
                    res++;
            }

            Console.WriteLine(res);
        }

        private static int Counter(int[] nbrs, int startPoint, int n)
        {
            int counter;
            int longestOccurance = 0;
            int freqNbr = -1;

            for (int i = startPoint; i < n; i += 2)
            {
                counter = 0;

                for (int j = startPoint; j < n && nbrs[j] != freqNbr; j += 2)
                {
                    if (nbrs[j] == nbrs[i])
                        counter++;
                }

                if (counter > longestOccurance)
                {
                    longestOccurance = counter;
                    freqNbr = nbrs[i];
                }
            }

            return freqNbr;
        }

        private static int Counter(int[] nbrs, int startPoint, int n, int excluded)
        {
            int counter;
            int longestOccurance = 0;
            int freqNbr = -1;

            for (int i = startPoint; i < n; i += 2)
            {
                counter = 0;

                for (int j = startPoint; j < n && nbrs[j] != freqNbr && nbrs[j] != excluded; j += 2)
                {
                    if (nbrs[j] == nbrs[i])
                        counter++;
                }

                if (counter > longestOccurance)
                {
                    longestOccurance = counter;
                    freqNbr = nbrs[i];
                }
            }

            return freqNbr;
        }
    }
}