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.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;

namespace AtCoder
{
    class Program
    {
        private static string Read() { return Console.ReadLine(); }
        private static int ReadInt() { return int.Parse(Read()); }
        private static long ReadLong() { return long.Parse(Read()); }
        private static double ReadDouble() { return double.Parse(Read()); }
        private static int[] ReadInts() { return Array.ConvertAll(Read().Split(), int.Parse); }
        private static long[] ReadLongs() { return Array.ConvertAll(Read().Split(), long.Parse); }
        private static double[] ReadDoubles() { return Array.ConvertAll(Read().Split(), double.Parse); }

        static int Solve(int N, int[] V)
        {
            var e = new Dictionary<int, int>();
            var o = new Dictionary<int, int>();
            e[0] = 0;
            o[0] = 0;
            for (int i = 0; i < N; ++i)
            {
                if (i % 2 == 0)
                {
                    if (!e.ContainsKey(V[i])) { e[V[i]] = 0; }
                    ++e[V[i]];
                }
                else
                {
                    if (!o.ContainsKey(V[i])) { o[V[i]] = 0; }
                    ++o[V[i]];
                }
            }
            var x = e.ToArray();
            var y = o.ToArray();
            Array.Sort(x, (a, b) => b.Value.CompareTo(a.Value));
            Array.Sort(y, (a, b) => b.Value.CompareTo(a.Value));
            int e0 = x[0].Value;
            int o0 = y[0].Value;
            int e1 = x[1].Value;
            int o1 = y[1].Value;
            return (x[0].Key != y[0].Key) ? N - e0 - o0 : Math.Min(N - o0 - e1, N - o1 - e0);
        }
        static void Main(string[] args)
        {
            int N = ReadInt();
            var V = ReadInts();
            Console.WriteLine(Solve(N, V));
        }
    }
}