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: Accepted)

using System;
using System.Linq;
using System.Collections.Generic;
using static System.Console;
using System.Text;
using System.IO;

namespace AtCoder
{
    class Program
    {
        static public long[] Sarray() { return ReadLine().Split().Select(long.Parse).ToArray(); }
        static public List<long> Slist() { return ReadLine().Split().Select(long.Parse).ToList(); }


        static void Main(string[] args)
        {
            var N = Sarray()[0];
            var A = Sarray();
            var o = new Dictionary<long, long>();
            var e = new Dictionary<long, long>();
            Dictionary<long, long> t;
            o[-1] = 0;
            e[-1] = 0;
            for (var i = 0; i < A.Length; ++i)
            {
                if (i % 2 == 0)
                    t = o;
                else
                    t = e;
                if (!t.ContainsKey(A[i]))
                    t[A[i]] = 1;
                else
                    ++t[A[i]];
            }
            var oary = o.ToArray();
            Array.Sort(oary, (l, r) => (int)(r.Value - l.Value));
            long maxvo1 = oary[0].Key;
            long maxvo2 = oary[1].Key;
            var eary = e.ToArray();
            Array.Sort(eary, (l, r) => (int)(r.Value - l.Value));
            long maxve1 = eary[0].Key;
            long maxve2 = eary[1].Key;

            if (maxvo1 == maxve1)//最長が同じ文字
            {
                if (o[maxvo1] < e[maxve1])
                    N -= e[maxve1] + o[maxvo2];
                else if (e[maxve1] < o[maxvo1])
                    N -= o[maxvo1] + e[maxve2];
                else
                {
                    var max = Math.Max(o[maxvo2], e[maxve2]);
                    N -= o[maxvo1] + max;
                }
            }
            else
                N -= e[maxve1] + o[maxvo1];
            WriteLine(N);
        }
    }
}