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.util.Map;
import java.util.Scanner;
import java.util.TreeMap;


	public class Main {
		
		public static void main(String[] args) {

			Scanner sc = new Scanner(System.in);
			
			int n = sc.nextInt();
			TreeMap<Integer,Integer> m1 = new TreeMap<Integer,Integer>();
			TreeMap<Integer,Integer> m2 = new TreeMap<Integer,Integer>();
			int sum1 = 0;
			int max11 = 0;
			int key11 = 0;
			int max12 = 0;
			int key12 = 0;
			
			int sum2 = 0;
			int max21 = 0;
			int key21 = 0;
			int max22 = 0;
			int key22 = 0;
			
			for(int i=0;i<n/2;i++) {
				m1.merge(sc.nextInt(), 1, Integer::sum);
				m2.merge(sc.nextInt(), 1, Integer::sum);
			}
			
			for(Map.Entry<Integer, Integer> e : m1.entrySet()) {
				sum1 += e.getValue();
				if(max11<=e.getValue()) {
					max12 = max11;
					max11 = Math.max(max11, e.getValue());
					key12 = key11;
					key11 = e.getKey();
					continue;
				}
				
				if(max12<=e.getValue()) {
					max12 = Math.max(max12, e.getValue());
					key12 = e.getKey();
				}
				
				
			}
			
			for(Map.Entry<Integer, Integer> e : m2.entrySet()) {
				sum2 += e.getValue();
				if(max21<=e.getValue()) {
					max22 = max21;
					max21 = Math.max(max21, e.getValue());
					key22 = key21;
					key21 = e.getKey();
					continue;
				}
				if(max22<=e.getValue()) {
					max22 = Math.max(max22, e.getValue());
					key22 = e.getKey();
				}
			}
			
			/*
			System.out.println(m1);
			System.out.println(m2);
			System.out.println(key11);
			System.out.println(key12);
			System.out.println(key21);
			System.out.println(key22);
			*/
			if(m1.size()==1&&m1.equals(m2)) {
				System.out.println(n/2);
			}else {
				if(key11!=key21) {
					System.out.println(sum1+sum2-m1.get(key11)-m2.get(key21));
				}else {
					if(m1.get(key11)+m2.get(key22)>m1.get(key12)+m2.get(key21)) {
						System.out.println(sum1+sum2-m1.get(key11)-m2.get(key22));
					}else {
						System.out.println(sum1+sum2-m1.get(key12)-m2.get(key21));
					}
				}
			}
			
			
			
	    }
		
	}