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: Runtime Error)

using System;
class c
{
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        var v = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
        var even = new int[10001];
        var odd = new int[10001];
        for (int i = 0; i < n; i++)
        {
            if (i % 2 == 0) even[v[i]]++;
            else odd[v[i]]++;
        }
        int e1 = 0, e2 = 0, o1 = 0, o2 = 0;
        for (int i = 1; i <= 10000; i++)
        {
            if (even[i] >= even[e1])
            {
                e2 = e1;
                e1 = i;
            }
            else if (even[i] >= even[e2])
            {
                e2 = i;
            }
            if (odd[i] >= odd[o1])
            {
                o2 = o1;
                o1 = i;
            }
            else if (odd[i] >= odd[o2])
            {
                o2 = i;
            }
        }
        if (o1 == e1) Console.WriteLine(Math.Min(n - even[e2] - odd[o1], n - even[e1] - odd[o2]));
        else Console.WriteLine(n - even[e1] - odd[o1]);
    }
}