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.Scanner;
import java.util.*;
import java.util.Map.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        final int n = sc.nextInt();

        Map<Integer, Long> guu = new HashMap<>();
        Map<Integer, Long> kisu = new HashMap<>();
        guu.put(-1,0L);
        kisu.put(-1,0L);
        for (int i = 0; i < n; i++) {
            int x = sc.nextInt();
            if (i % 2 == 0) {
                if (guu.containsKey(x)) {
                    guu.put(x, guu.get(x) + 1L);
                    continue;
                }
                guu.put(x, 1L);
                continue;
            }
            if (kisu.containsKey(x)) {
                kisu.put(x, kisu.get(x) + 1L);
                continue;
            }
            kisu.put(x, 1L);
        }

        List<Entry<Integer, Long>> list_guu = createList(guu);
        List<Entry<Integer, Long>> list_kisu = createList(kisu);

        if (list_guu.get(0).getKey() == list_kisu.get(0).getKey()) {
            long ans1 = list_guu.get(0).getValue() + list_kisu.get(1).getValue();
            long ans2 = list_guu.get(1).getValue() + list_kisu.get(0).getValue();
            long cnt = n - Math.max(ans1, ans2);
            System.out.println(cnt);
        } else {
            long ans = list_guu.get(0).getValue() + list_kisu.get(0).getValue();
            long cnt = n - ans;
            System.out.println(cnt);
        }
    }
    public static List<Entry<Integer, Long>> createList(Map<Integer, Long> map) {
        List<Entry<Integer, Long>> list_entries =
            new ArrayList<Entry<Integer, Long>>(map.entrySet());
        Collections.sort(list_entries, new Comparator<Entry<Integer, Long>>() {
            @Override
            public int compare(Entry<Integer, Long> obj1, Entry<Integer, Long> obj2) {
                return obj2.getValue().compareTo(obj1.getValue());
            }
        });
        return list_entries;
    }
}