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 Scala (2.11.7) (judge verdict: Accepted)

import java.util.Scanner

import scala.collection.mutable
import scala.collection.mutable.ArrayBuffer

object Main {
  def main(args: Array[String]) {
    val result = solve(new Scanner(System.in))
    if (result.length > 0) println(result)
  }

  def solve(in: String): String = solve(new Scanner(in))

  def solve(sc: Scanner): String = {
    val n = sc.nextInt
    val v1 = new mutable.HashMap[Int, Int]()
    val v2 = new mutable.HashMap[Int, Int]()
    for (i <- 0 until n / 2) {
      val k1 = sc.nextInt
      v1(k1) = v1.getOrElse(k1, 0) + 1
      val k2 = sc.nextInt
      v2(k2) = v2.getOrElse(k2, 0) + 1
    }

    val l1 = v1.toList.sortBy(_._2).reverse.take(2)
    val l2 = v2.toList.sortBy(_._2).reverse.take(2)
    if (l1(0)._1 == l2(0)._1) {
      if (l1.length > 1) {
        val m1 = n - l1(0)._2 - l2(1)._2
        val m2 = n - l1(1)._2 - l2(0)._2
        List(m1, m2).min.toString
      } else (n / 2).toString
    } else {
      (n - l1(0)._2 - l2(0)._2).toString
    }
  }
}