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.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;

public class Main {


    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
    	Map<Integer, Integer> a = new HashMap<Integer, Integer>();
    	Map<Integer, Integer> b = new HashMap<Integer, Integer>();
    	int n=sc.nextInt();
    	for(int i=0;i<n/2;i++) {
    		int v=sc.nextInt();
    		if(a.containsKey(v))a.put(v, a.get(v)+1);
    		else a.put(v, 1);
    		v=sc.nextInt();
    		if(b.containsKey(v))b.put(v, b.get(v)+1);
    		else b.put(v, 1);
    	}
        //Map.Entry
        List<Entry<Integer, Integer>> list_entries = new ArrayList<Entry<Integer, Integer>>(b.entrySet());
        List<Entry<Integer, Integer>> list_entries2 = new ArrayList<Entry<Integer, Integer>>(a.entrySet());
        //Comparator(昇順)
        Collections.sort(list_entries, new Comparator<Entry<Integer, Integer>>() {
            public int compare(Entry<Integer, Integer> obj1, Entry<Integer, Integer> obj2) {
            	//昇順 return obj1.getValue().compareTo(obj2.getValue());
                 return obj2.getValue().compareTo(obj1.getValue());
            }
        });
        Collections.sort(list_entries2, new Comparator<Entry<Integer, Integer>>() {
            public int compare(Entry<Integer, Integer> obj1, Entry<Integer, Integer> obj2) {
            	//昇順 return obj1.getValue().compareTo(obj2.getValue());
                 return obj2.getValue().compareTo(obj1.getValue());
            }
        });
int ans=0;int number_a=0;
        for(Entry<Integer, Integer> entry : list_entries) {
           number_a=entry.getKey();
           ans+=n/2-entry.getValue();
           break;
        }
int ans2=0; int number_b=0;
        for(Entry<Integer, Integer> entry : list_entries2) {
            number_b=entry.getKey();
            ans2+=n/2-entry.getValue();
            break;
         }
        if(ans==0&&ans2==0&&number_a==number_b)System.out.println(n/2);
        else if(number_a!=number_b) System.out.println(ans+ans2);
        else {
        	int exans=0;int count=0;
            for(Entry<Integer, Integer> entry : list_entries) {
                if(count ==1) {
                	//number_a=entry.getKey();
                    exans+=n/2-entry.getValue();
                    break;
                }
                	count++;
             }
            int exans2=0;count=0;
            for(Entry<Integer, Integer> entry : list_entries2) {
                if(count ==1) {
                	//number_a=entry.getKey();
                    exans2+=n/2-entry.getValue();
                    break;
                }
                	count++;
             }
            System.out.println(Math.min(exans+ans2,ans+exans2));

        }
    }

}