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
    $N = trim(fgets(STDIN));
    $input = explode(" ",trim(fgets(STDIN)));
    $a_miss = 0;
    $b_miss = 0;
    $c_miss = 0;
    $d_miss = 0;
        
    for ($i = 0; $i < $N; $i++){
        $num[$i] = intval($input[$i]);
        if ($i == 1){
            $a = $num[0];
            $b = $num[1];
        } elseif ($i % 2 == 0 && $i > 1) {
            if ($num[$i] != $a) $a_miss++;
        } elseif ($i % 2 == 1 && $i > 1) {
            if ($num[$i] != $b) $b_miss++;
        }
    }
    
    $c = $num[2];
    $d = $num[3];
    
    for ($i = 0; $i < $N; $i++){
        $num[$i] = intval($input[$i]);
        if ($i % 2 == 0) {
            if ($num[$i] != $c) $c_miss++;
        } elseif ($i % 2 == 1) {
            if ($num[$i] != $d) $d_miss++;
        }
    }
    
    if ($a_miss + $b_miss > $c_miss + $d_miss) {
        $a_miss = $c_miss;
        $b_miss = $d_miss;
    }
    if ($a == $b) $a_miss = $N / 2;
    echo $a_miss + $b_miss;
?>