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 Kotlin (1.0.0) (judge verdict: Accepted)

fun ac103(args: Array<String>) {
    val numList = args[1].split(" ").map { it.toInt() }
    val evenNumToCount = mutableMapOf(0 to 0)
    val oddNumToCount = mutableMapOf(0 to 0)
    numList.forEachIndexed { index, num ->
        if (index % 2 == 0) {
            if (!evenNumToCount.containsKey(num)) {
                evenNumToCount[num] = 0
            }
            evenNumToCount[num] = evenNumToCount[num]!! + 1
        } else {
            if (!oddNumToCount.containsKey(num)) {
                oddNumToCount[num] = 0
            }
            oddNumToCount[num] = oddNumToCount[num]!! + 1
        }
    }

    val evenSorted = evenNumToCount.entries.sortedByDescending { it.value }
    val oddSorted = oddNumToCount.entries.sortedByDescending { it.value }
    if (evenSorted[0].key != oddSorted[0].key) {
        println(numList.size - evenSorted[0].value - oddSorted[0].value)
    } else {
        println(Math.min(numList.size - evenSorted[0].value - oddSorted[1].value,
                numList.size - evenSorted[1].value - oddSorted[0].value))

    }
}

fun main(args: Array<String>) {
    ac103(readLineList())
}

fun readLineList(): Array<String> {
    val lineList = mutableListOf<String>()
    while (true) {
        val line = readLine()
        if (line.isNullOrBlank()) {
            break
        } else {
            lineList.add(line!!)
        }
    }
    return lineList.toTypedArray()
}