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 (2.13.1) (judge verdict: Wrong Answer)

object Main extends App {
  import scala.io.StdIn.{readInt, readLine}
  val _ = readInt()
  val numbers = readLine().split(' ').map(_.toInt)

  val Array(first, second) = numbers.take(2)

  def findMaxAppearNumber(values: Seq[Int]): Int = {
    values.groupMapReduce(identity)(_ => 1)(_ + _).max._1
  }

  def computeChangeCount(values: Seq[Int]): Int = {
    val maxAppearedNumber = findMaxAppearNumber(values)
    values.count(_ != maxAppearedNumber)
  }

  val suggestedChangeSize = if (first == second) {
    0
  } else {
    val (odds, evens) = numbers.zipWithIndex.partition(_._2 % 2 == 0)
    computeChangeCount(odds.map(_._1)) + computeChangeCount(evens.map(_._1))
  }

  println(suggestedChangeSize)
}