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

            int check1 = nbrs[0];
            int check2 = nbrs[1];

            int sum = 0;

            for (int i = 2; i < (n + 2) / 2; )
            {
                int c1 = nbrs[i];
                int c2 = nbrs[i + 1];

                if (check2 == c1)
                    sum += 2;
                if (check1 != c1)
                    sum += 1;
                if (check2 != c2)
                    sum += 1;

                i += 2;
            }
            Console.WriteLine(sum);
        }
    }
}