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.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] od = new int[100001];
        int[] ev = new int[100001];
        int[] p = new int[4];
        int[] q = new int[4];
        for(int i = 0; i < n/2;i++){
            int ai = sc.nextInt();
            od[ai]++;
            if(q[0] < od[ai]){
                if(p[0] != ai){   
                    p[1] = p[0];    q[1] = q[0];
                }
                p[0] = ai;  q[0] = od[ai]; 
            }else if(q[1] < od[ai]){
                p[1] = ai;   q[1] = od[ai];   
            }
            ai = sc.nextInt();
            ev[ai]++;
            if(q[2] < ev[ai]){
                if(p[2] != ai){
                    p[3] = p[2];    q[3] = q[2];
                }
                p[2] = ai;   q[2] = ev[ai];
            }else if(q[3] < ev[ai]){
                p[3] = ai;   q[3] = ev[ai];
            }
        }
        if(p[0] != p[2])    System.out.println(n-q[0]-q[2]);
        else System.out.println(Math.min((n-q[0]-q[3]), (n-q[1]-q[2])));
    }
}