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 int mode(int[]a) {
		int count = 1;
		int maxcount = 1;
		int mode = a[0];
		for(int i = 1; i < a.length; i++) {
			if(a[i] == a[i-1]) {
				count += 1;
				if(count >= maxcount) {
					mode = a[i];
					maxcount = count;
				}
			}
			else
				count = 1;
		}
		return mode;
	}
	public static int mode2(int[]a, int mode) {
		int count = 1;
		int maxcount = 1;
		int mode2;
		if(a[0] != mode) mode2 = a[0];
		else mode2 = 0;
		for(int i = 1; i < a.length; i++) {
			if(a[i] == mode) continue;
			if(a[i] == a[i-1]) {
				count += 1;
				if(count >= maxcount) {
					mode2 = a[i];
					maxcount = count;
				}
			}
			else {
				count = 1;
				if(mode2 == 0)
					mode2 = a[i];
			}
		}
		return mode2;
	}
	public static int count(int[]a, int x) {
		int count = 0;
		for(int i = 0; i < a.length; i++) {
			if(a[i] == x)
				count += 1;	
		}
		return count;
	}
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] vodd = new int[n/2];
		int[] veven = new int[n/2];
		for(int i = 0; i < n/2; i++) {
			vodd[i] = sc.nextInt();
			veven[i] = sc.nextInt();
		}
		Arrays.sort(vodd);
		Arrays.sort(veven);
		int modevodd = mode(vodd);
		int modeveven = mode(veven);
		int modenumvodd = count(vodd, modevodd);
		int modenumveven = count(veven, modeveven);
		if(modevodd != modeveven)
			System.out.println(n - modenumvodd - modenumveven);
		else
			System.out.println(Math.min(n - modenumvodd - count(veven, mode2(veven, modeveven)),n - count(vodd, mode2(vodd, modevodd)) - modenumveven));
	}

}