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: Accepted)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int n = Integer.parseInt(br.readLine());

		String str[] = br.readLine().split(" ");
		int even[] = new int[100005];
		int odd[] = new int[100005];

		for (int i = 0; i < n; i++) {
			int v = Integer.parseInt(str[i]);
			if (i % 2 == 0)
				even[v]++;
			else
				odd[v]++;
		}

		int maxE = 0;
		int maxO = 0;
		int maxEE = 0;
		int maxOO = 0;

		int maxEI = 0;
		int maxOI = 0;

		for (int i = 0; i < 100005; i++) {
			if (maxE < even[i]) {
				maxE = even[i];
				maxEI = i;
			}
			if (maxO < odd[i]) {
				maxO = odd[i];
				maxOI = i;
			}
		}

		if (maxEI == maxOI) {
			for (int i = 0; i < 100005; i++) {
				if (maxEE < even[i] && i != maxEI) {
					maxEE = even[i];
				}
				if (maxOO < odd[i] && i != maxOI) {
					maxOO = odd[i];
				}
			}
			int ans = Math.min(n - maxE - maxOO, n - maxEE - maxO);
			System.out.println(ans);
		} else
			System.out.println(n - maxE - maxO);

	}
}