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.*;

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

		int n = sc.nextInt();

		int a[] = new int[n];
		int cnt1[] = new int[100001];
		int cnt2[] = new int[100001];
		
		for(int i=0;i<n;i++){
			a[i] = sc.nextInt();
		}

		for(int i=0;i<n;i+=2){
			cnt1[a[i]]++;
			cnt2[a[i+1]]++;				
		}

		int max1=0, max2=0;
		for(int i=0;i<100001;i++){
			if(cnt1[i] >= cnt1[max1])
				max1 = i;
			if(cnt2[i] >= cnt2[max2])
				max2 = i;
		}

		if(max1 == max2){
			int t1 = 0, t2=0;
			for(int i=0;i<100001;i++){
				if(cnt1[i] >= cnt1[t1] && i != max2)
					t1 = i;
				if(cnt2[i] >= cnt2[t2] && i != max1)
					t2 = i;
			}
			
			System.out.println(Math.min((n/2-cnt1[max1]) + (n/2-cnt2[t2]), 
				(n/2-cnt1[t1]) + (n/2-cnt2[max2])));
		}
		else{
			System.out.print((n/2-cnt1[max1]) + (n/2-cnt2[max2]));
		}
	}
}