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: Wrong Answer)

import java.util.HashMap;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] v = new int[n];
		HashMap<String, Integer> first = new HashMap<String, Integer>();
		HashMap<String, Integer> second = new HashMap<String, Integer>();
		int ans = 0, fmax = 1, smax = 1;

		for (int i = 0; i < n; i++) {
			v[i] = sc.nextInt();
			if (i % 2 == 0) {
				if (first.get(String.valueOf(v[i])) != null) {
					first.put(String.valueOf(v[i]), first.get(String.valueOf(v[i])) + 1);
					if (first.get(String.valueOf(v[i])) > fmax) {
						fmax = first.get(String.valueOf(v[i]));
					}
				} else {
					first.put(String.valueOf(v[i]), 1);
				}
			} else {
				if (second.get(String.valueOf(v[i])) != null) {
					second.put(String.valueOf(v[i]), second.get(String.valueOf(v[i])) + 1);
					if (second.get(String.valueOf(v[i])) > smax) {
						smax = second.get(String.valueOf(v[i]));
					}
				} else {
					second.put(String.valueOf(v[i]), 1);
				}
			}
		}

		if (first.size() > 1) {
			if (n % 2 == 0) {
				ans = (n / 2) - fmax;
			} else {
				ans = (n / 2) - fmax + 1;
			}
		}

		if (second.size() > 1) {
			ans += (n / 2) - smax;
		}

		if (ans == 0 && v[0] == v[1]) {
			ans = n / 2;
		}

		System.out.println(ans);

		sc.close();
	}

}