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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

(function(input) {
  'use strict';

  //var input = '10\n8 4 8 3 8 2 8 1 8 4\n'
  //var input = '4\n3 2 3 1\n'
  //var input = '6\n105 119 105 119 105 119\n'
  //var input = '6\n1 1 1 1 1 1\n'

  var n = 0
  var ary = []
  input.split("\n").some(function(line) {
    if (n == 0) {
      n = parseInt(line, 10)
    } else {
      ary = line.split(' ').map((x) => { return parseInt(x, 10)})
      return true
    }
  })

  var hash = {}
  var maxKey = 0
  for (var i = 0, len = ary.length; i < len; i++) {
    if (hash[ary[i]] === undefined) {
      hash[ary[i]] = 0
    }
    hash[ary[i]] += 1
    if (maxKey < hash[ary[i]]) {
      maxKey = ary[i]
    }
  }

  var objLength = Object.keys(hash).length

  delete hash[maxKey]
  objLength -= 1

  if (objLength == 0) {
    console.log(n/2)
    return
  }

  var secondMax = -1
  if (objLength == 1) {
    for (var i in hash) {
      secondMax = i
    }
  } else {
    for (var i in hash) {
      if (secondMax == -1) {
        secondMax = hash[i]
        continue
      }
      if (secondMax < hash[i]) {
        secondMax = i
      }
    }
  }

  delete hash[secondMax]
  objLength -= 1

  // console.log('secondMax')
  // console.log(secondMax)
  // console.log(hash)

  console.log(objLength)

})(require('fs').readFileSync('/dev/stdin', 'utf8'))