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: Runtime Error)

import java.io.{BufferedOutputStream, BufferedReader, InputStreamReader, PrintWriter}

import scala.collection.mutable.ArrayBuffer

object Main {
  def main(args: Array[String]): Unit = {
    val in = new BufferedReader(new InputStreamReader(System.in))
    val out = new PrintWriter(new BufferedOutputStream(System.out))
    val n = in.readLine().toInt
    val vs = in.readLine().split("\\s+").map(_.toInt)

    val evenCount = Array.ofDim[Int](100000)
    val oddCount = Array.ofDim[Int](100000)

    for (i <- 0 until (n / 2) ) {
      evenCount(vs(i * 2)) += 1
      oddCount(vs(i * 2 + 1)) += 1
    }

    val evenCountDesc = evenCount.zipWithIndex.sorted(Ordering.by[(Int, Int), Int](_._1).reverse)
    val oddCountDesc = oddCount.zipWithIndex.sorted(Ordering.by[(Int, Int), Int](_._1).reverse)

    out.println(
      n - {
        if (evenCountDesc(0)._2 == oddCountDesc(0)._2) {
          Math.max(
            evenCountDesc(0)._1 + {
              if (oddCountDesc.length == 1) {
                0
              } else {
                oddCountDesc(1)._1
              }
            },
            oddCountDesc(0)._1 + {
              if (evenCountDesc.length == 1) {
                0
              } else {
                evenCountDesc(1)._1
              }
            }
          )
        } else {
          evenCountDesc(0)._1 + oddCountDesc(0)._1
        }
      }
    )

    out.flush()
  }
}