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

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

		HashMap<Integer, Integer> mapEv = new HashMap<>();
		HashMap<Integer, Integer> mapOd = new HashMap<>();
		ArrayList<Integer> evlist = new ArrayList<>();
		ArrayList<Integer> odlist = new ArrayList<>();

		for (int i = 0; i < n; i++) {
			if (i%2 == 0) {
				int num = sc.nextInt();
				if (mapEv.containsKey(num)) {
					int cnt = mapEv.get(num);
					mapEv.put(num, cnt+1);
				} else {
					mapEv.put(num, 1);
					evlist.add(num);
				}
			} else {
				int num = sc.nextInt();
				if (mapOd.containsKey(num)) {
					int cnt = mapOd.get(num);
					mapOd.put(num, cnt+1);
				} else {
					mapOd.put(num, 1);
					odlist.add(num);
				}
			}
		}

		int Amax1Number = 0;
		int Amax2Number = 0;
		int Amax1 = 0;
		int Amax2 = 0;

		int Bmax1Number = 0;
		int Bmax2Number = 0;
		int Bmax1 = 0;
		int Bmax2 = 0;
		int ans = 0;

		//パターンA
		for (int i = 0; i < evlist.size(); i++) {
			int tmp = mapEv.get(evlist.get(i));
			if (Amax1 <= tmp) {
				Amax2 = Amax1;
				Amax1 = tmp;
				Amax2Number = Amax1Number;
				Amax1Number = evlist.get(i);
			} else if (Amax2 <= tmp) {
				Amax2 = tmp;
			}
		}
		//パターンB
		for (int i = 0; i < odlist.size(); i++) {
			int tmp = mapOd.get(odlist.get(i));
			if (Bmax1 <= tmp) {
				Bmax2 = Bmax1;
				Bmax1 = tmp;
				Bmax2Number = Bmax1Number;
				Bmax1Number = odlist.get(i);
			} else if (Bmax2 <= tmp) {
				Bmax2 = tmp;
			}
		}
		if (Amax1Number == Bmax1Number) {
			//どちらの場合が良いか判定
			if (Amax1 + Bmax2 < Amax2 + Bmax1) {
				ans = n - Amax2 - Bmax1;
			} else {
				ans = n - Amax1 - Bmax2;
			}
		} else {
			ans = n - Amax1 - Bmax1;
		}
		System.out.println(ans);
	}
}