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 void main(String[] args) { 
      Scanner sc = new Scanner(System.in);
      int n = sc.nextInt();
      int[] arr = new int[n];
      for(int i = 0; i < n; i++)
        arr[i] = sc.nextInt();

      Map<Integer, Integer> oddFreq = new HashMap<>();
      Map<Integer, Integer> evenFreq = new HashMap<>();

      for(int i = 0; i < n; i++) {
        if(i % 2 == 0)
          evenFreq.put(arr[i], evenFreq.getOrDefault(arr[i], 0) + 1);
        else
          oddFreq.put(arr[i], oddFreq.getOrDefault(arr[i], 0) + 1);
      }

      List<Map.Entry<Integer, Integer>> oddList = new ArrayList<>(oddFreq.entrySet());
      List<Map.Entry<Integer, Integer>> evenList = new ArrayList<>(evenFreq.entrySet());
      Collections.sort(oddList, (e1, e2) -> e2.getValue() - e1.getValue());
      Collections.sort(evenList, (e1, e2) -> e2.getValue() - e1.getValue());
      
      if(oddList.get(0).getKey() - evenList.get(0).getKey() != 0)
        System.out.println(n - oddList.get(0).getValue() - evenList.get(0).getValue());
      else {
          
        int oddCnt = oddList.size() <= 1 ? 0 : oddList.get(1).getValue();
        int evenCnt = evenList.size() <= 1 ? 0 : evenList.get(1).getValue();
        System.out.println(n - Math.max(oddList.get(0).getValue() + evenCnt, evenList.get(0).getValue() + oddCnt));
      }

  }
}