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 static System.Console;
using static System.Math;
 
public class Hello{
    public static void Main(){
        int kazu = int.Parse(ReadLine());
        int[] even = new int[kazu/2];
        int[] odd = new int[kazu/2];
        string[] suretu = ReadLine().Split(' ');
        for(int i=0;i<kazu;i++){
            int temp = int.Parse(suretu[i]);
            if(i%2==0){
                even[i/2] = temp;
            }else{
                odd[i/2] = temp;
            }
        }
        
        int[] counttemp = new int[110000];
        int[] saihine = new int[2];
        int[] countse = new int[2];
        for(int i=0;i<kazu/2;i++){
            int temp = even[i];
            counttemp[temp]++;
        }
        for(int i=0;i<=100001;i++){
            if(counttemp[i] > countse[1]){
                if(counttemp[i] > countse[0]){
                    countse[1] = countse[0];
                    countse[0] = counttemp[i];
                    saihine[1] = saihine[0];
                    saihine[0] = i;
                }else{
                    countse[1] = counttemp[i];
                    saihine[1] = i;
                }
            }
        }
        
        int[] counttemp2 = new int[110000];
        int[] saihino = new int[2];
        int[] countso = new int[2];
        for(int i=0;i<kazu/2;i++){
            int temp = odd[i];
            counttemp2[temp]++;
        }
        for(int i=0;i<=100001;i++){
            if(counttemp2[i] > countso[1]){
                if(counttemp2[i] > countso[0]){
                    countso[1] = countso[0];
                    countso[0] = counttemp2[i];
                    saihino[1] = saihino[0];
                    saihino[0] = i;
                }else{
                    countso[1] = counttemp2[i];
                    saihino[1] = i;
                }
            }
        }
        
        if(saihine[0] == saihino[0]){
            int ans1 = kazu-(countse[0]+countso[1]);
            int ans2 = kazu-(countse[1]+countso[0]);
            WriteLine(Min(ans1,ans2));
        }else{
            int ans = kazu-(countse[0]+countso[0]);
            WriteLine(ans);
        }
    }
}