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 PHP7 (7.0.15) (judge verdict: Accepted)

<?php
// C
fscanf(STDIN, '%d', $n);
$v = array_map('intval', explode(' ', trim(fgets(STDIN))));

for ($i = 0; $i < $n; $i++) {
    if ($i % 2 === 0) {
        if (isset($vk_cnt[$v[$i]])) {
            $vk_cnt[$v[$i]]++;
        } else {
            $vk_cnt[$v[$i]] = 1;
        }
    } else {
        if (isset($vg_cnt[$v[$i]])) {
            $vg_cnt[$v[$i]]++;
        } else {
            $vg_cnt[$v[$i]] = 1;
        }
    }
}
$qk = new SplPriorityQueue;
$qg = new SplPriorityQueue;

foreach ($vk_cnt as $i => $cnt) {
    $qk->insert([$i, $cnt], $cnt);
}
foreach ($vg_cnt as $i => $cnt) {
    $qg->insert([$i, $cnt], $cnt);
}

$vk = $qk->extract();
$vg = $qg->extract();
if ($vk[0] === $vg[0]) {
    if (!$qk->isEmpty()) {
        $vk2 = $qk->extract();
    } else {
        $vk2 = [-1, 0];
    }

    if (!$qg->isEmpty()) {
        $vg2 = $qg->extract();
    } else {
        $vg2 = [-1, 0];
    }

    if ($vk[1] + $vg2[1] > $vk2[1] + $vg[1]) {
        $vg = $vg2;
    } else {
        $vk = $vk2;
    }
}
$ans = count($v) - $vk[1] - $vg[1];
echo $ans;