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 PHP (5.6.30) (judge verdict: Wrong Answer)

<?php
//error_reporting(0);
$N = trim(fgets(STDIN));
//list($A,$B) = explode(" ",trim(fgets(STDIN)));
$v = explode(" ",trim(fgets(STDIN)));

$o=array_map('current', array_chunk($v, 2));
$e=array_map('current', array_chunk(array_slice($v, 1), 2));

$oc = array_count_values($o);
$ec = array_count_values($e);

arsort($oc);
arsort($ec);

foreach($oc as $k=>$v) {
  $okey = $k;
  $oval = $v;
  $ocnt = $N / 2 - $v;
  break;
}
foreach($ec as $k=>$v) {
  $eekey = $k;
  $eeval = $v;
  $eecnt = $N / 2 - $v;
  if ($eekey != $okey) {
    break;
  }
}
if ($eekey == $okey) {
  $ocnt = $N /2;
  $eecnt = 0;
}

printf("%d\n",$ocnt+$eecnt);