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);
        int n = sc.nextInt();
        Map<Integer, Integer> guu = new HashMap<>();
        Map<Integer, Integer> kisu = new HashMap<>();
        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) + 1);
                    continue;
                }
                guu.put(x, 1);
                continue;
            }
            if (kisu.containsKey(x)) {
                kisu.put(x, kisu.get(x) + 1);
                continue;
            }
            kisu.put(x, 1);
        }
        List<Entry<Integer, Integer>> list_entries =
            new ArrayList<Entry<Integer, Integer>>(guu.entrySet());
        Collections.sort(list_entries, new Comparator<Entry<Integer, Integer>>() {
            public int compare(Entry<Integer, Integer> obj1, Entry<Integer, Integer> obj2) {
                return obj2.getValue().compareTo(obj1.getValue());
            }
        });
        List<Entry<Integer, Integer>> list_entries2 =
            new ArrayList<Entry<Integer, Integer>>(kisu.entrySet());
        Collections.sort(list_entries2, new Comparator<Entry<Integer, Integer>>() {
            public int compare(Entry<Integer, Integer> obj1, Entry<Integer, Integer> obj2) {
                return obj2.getValue().compareTo(obj1.getValue());
            }
        });
        int max = 0;
        int cnt = 0;
        int cnt2 = 0;
        if (list_entries.get(0).getKey() == list_entries2.get(0).getKey()) {
            max = list_entries.get(0).getValue();
            cnt += n / 2 - max;
            if (list_entries2.size() == 1) {
                cnt += n / 2;
            } else {
                cnt += n / 2 - list_entries2.get(1).getValue();
            }
            max = list_entries2.get(0).getValue();
            cnt2 += n / 2 - max;
            if (list_entries.size() == 1) {
                cnt2 += n / 2;
            } else {
                cnt2 += n / 2 - list_entries.get(1).getValue();
            }
            System.out.println(Math.min(cnt, cnt2));
            return;
        }
        cnt += n / 2 - list_entries.get(0).getValue();
        cnt += n / 2 - list_entries2.get(0).getValue();
        System.out.println(cnt);
    }
}