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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;
class Main
{
    public static void main (String[] args)
    {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] a = new int[n/2];
        int[] b = new int[n/2];
 
        for(int i = 0; i < n/2; i++){
            a[i] = sc.nextInt();
            b[i] = sc.nextInt();
        }
 
        int ans_a1 = 1;
        int ans_a2 = 1;
        int ans_b1 = 1;
        int ans_b2 = 1;
        
        Arrays.sort(a);
        Arrays.sort(b);
 
        int k = 1; 
        int l = 1;
        int x1 = a[0];
        int y1 = b[0];
 
        for(int i = 1; i < n/2; i++){
            if(a[i] == a[i-1]){
                k++;
                if(ans_a1 <= k){
                    ans_a2 = ans_a1;
                    ans_a1 = k;
                    x1 = a[i-1];
                }
                else if(ans_a2 <= k)
                    ans_a2 = k;
            }
            else
                k = 1;
        }
        for(int i = 1; i < n/2; i++){
            if(b[i] == b[i-1]){
                l++;
                if(ans_b1 <= l){
                    ans_b2 = ans_b1;
                    ans_b1 = l;
                    y1 = b[i-1];
                }
                else if(ans_b2 <= l)
                    ans_b2 = l;
            }
            else
                l = 1;
        }
        int ans = n - (ans_a1 + ans_b1);
        if(ans_a1 == n/2) ans_a2 = 0;
        if(ans_b1 == n/2) ans_b2 = 0;
        if(x1 == y1)
            ans = Math.min(n - (ans_a1 + ans_b2), n - (ans_b1 + ans_a2));
        System.out.println(ans);
    }
}