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

namespace ABC111
{
    class C
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] v = Console.ReadLine().Split().Select(int.Parse).ToArray();

            //StreamReader sr = new StreamReader(@"./testcase/testcase");
            //int n = int.Parse(sr.ReadLine());
            //int[] v = sr.ReadLine().Split().Select(int.Parse).ToArray();

            Dictionary<int, int> dictOdd = new Dictionary<int, int>();
            Dictionary<int, int> dictEven = new Dictionary<int, int>();

            // Odd
            int oddMaxKey = 0;
            int oddMaxValue = 0;
            for (int i = 0; i < n; i += 2)
            {
                if (!dictOdd.ContainsKey(v[i])) dictOdd.Add(v[i], 1);
                else dictOdd[v[i]]++;
                if (oddMaxValue < dictOdd[v[i]]) { oddMaxKey = v[i]; oddMaxValue = dictOdd[v[i]]; }
            }

            // Even
            int evenMaxKey = 0;
            int evenMaxValue = 0;
            for (int i = 1; i < n; i += 2)
            {
                if (!dictEven.ContainsKey(v[i])) dictEven.Add(v[i], 1);
                else dictEven[v[i]]++;
                if (evenMaxValue < dictEven[v[i]]) { evenMaxKey = v[i]; evenMaxValue = dictEven[v[i]]; }
            }

            int oddSum = 0;
            int oddIndex = 0;
            int oddSecondMaxKey = 0;
            foreach (var i in dictOdd.OrderBy(x => x.Value))
            {
                oddSum += i.Value;
                if (oddIndex == dictOdd.Count - 1) { oddSecondMaxKey = i.Key; }
                oddIndex++;
            }

            //Console.WriteLine(oddSum);

            int evenSum = 0;
            int evenIndex = 0;
            int evenSecondMaxKey = 0;
            foreach (var i in dictEven.OrderBy(x => x.Value))
            {
                evenSum += i.Value;
                if (evenIndex == dictEven.Count - 1) { evenSecondMaxKey = i.Key; }
                evenIndex++;
            }

            if (evenMaxKey == oddMaxKey)
            {
                if (evenMaxValue < oddMaxValue)
                {
                    Console.WriteLine(oddSum - dictOdd[oddMaxKey] + evenSum - dictEven[evenSecondMaxKey]);
                }
                else
                {
                    Console.WriteLine(oddSum - dictOdd[oddSecondMaxKey] + evenSum - dictEven[evenMaxKey]);
                }
            }
            else
            {
                Console.WriteLine(oddSum - dictOdd[oddMaxKey] + evenSum - dictEven[evenMaxKey]);
            }
        }
    }
}