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 Java (OpenJDK 11.0.6) (judge verdict: Runtime Error)

import java.util.ArrayList;
import java.util.Scanner;

public class Main {
	static int n;
	static int[] m;
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);

		n=sc.nextInt();
		m=new int[n];
		ArrayList<Integer> num=new ArrayList<>();
		ArrayList<Integer> num2=new ArrayList<>();
		int ans=0;

		for (int i = 0; i < n; i++) {
			m[i]=sc.nextInt();
			if(i%2==0 &&!num2.contains(m[i])) num2.add(m[i]);
			else if(i%2==1 && !num.contains(m[i])) num.add(m[i]);
		}

		if(num.size()==1 && num2.size()==1 && num.get(0)==num2.get(0)) {
			System.out.println(n/2);
			System.exit(1);	
		}

		for (int i = 0; i < n; i++) 
			if(i%2==0 && m[i]!= num2.get(max(num2))|| i%2!=0 && m[i]!= num.get(max(num))) ans++;

		System.out.println(ans);
	}

	public static int max(ArrayList<Integer> num) {
		int a=0,ans=0;
		for (int i = 0; i < num.size(); i++) 
			for (int j=0; j<n; j++) {
				int c=0;
				if(num.get(i)==m[j]) c++;
				if(a<c) {
					a=c;
					ans=i; 
					break;
				}
			}
		return ans;
	}
}