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.io.*;
import java.math.*;
import java.util.*;
public class Main{

	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		int N = input.nextInt();
		int[][] even = new int[100001][2]; //[Number of occurances, which number is analyzed]
		//Needed due to sorting mixing indices up
		int[][] odd = new int[100001][2];
		int ans = 0;
		for (int i = 0; i < N; i++) {
			int x = input.nextInt();
			if (i%2==0) {
				even[x][0]++;
				even[x][1]=x;
			} 
			else {
				odd[x][0]++;
				odd[x][1]=x;
			} 
		}
		Arrays.sort(even,(a,b)->Integer.compare(a[0], b[0]));
		Arrays.sort(odd,(a,b)->Integer.compare(a[0], b[0]));
		if (even[100000][1]!=odd[100000][1]) {
			ans+=N/2-even[100000][0];
			ans+=N/2-odd[100000][0];
		}else {
			int sub = Math.max(even[100000][0]+odd[99999][0], odd[100000][0]+even[99999][0]);
			ans+=N-sub;
		}
		System.out.println(ans);
	}
}