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));
$v = explode(" ", trim(fgets(STDIN)));
$times = 0;

for($i = 0; $i < count($v); $i+=2){
	$odd[] = $v[$i];
}
for($i = 1; $i < count($v); $i+=2){
	$even[] = $v[$i];
}
//$count = array_count_values($v);
$odd_count = array_count_values($odd);
$even_count = array_count_values($even);
arsort($odd_count);
arsort($even_count);
$odd_keys = array_keys($odd_count);
$even_keys = array_keys($even_count);
$odd_values = array_values($odd_count);
$even_values = array_values($even_count);

/*var_dump($odd_count);
var_dump($even_count);
var_dump($odd_keys);
var_dump($even_keys);
var_dump($odd_values);
var_dump($even_values);
var_dump($odd_keys[0]);
var_dump($even_keys[0]);*/

if($odd_keys[0] != $even_keys[0]){
	if(count($odd_values) > 1){
		$times+=(count($odd) - $odd_values[0]);
	}
	if(count($even_values) > 1){
		$times+=(count($even) - $even_values[0]);
	}
}else{
	if($odd_values[0] > $even_values[0]){
		if(count($odd_values) > 1){
			$times+=(count($odd) - $odd_values[0]);
		}
		if(count($even_values) > 1){
			$times+=(count($even) - $even_values[1]);
		}
	}else{
		if(count($odd_values) > 1){
			$times+=(count($odd) - $odd_values[1]);
		}
		if(count($even_values) > 1){
			$times+=(count($even) - $even_values[0]);
		}
	}
	if($times == 0){
		$times = 2;
	}
}

printf("%d", $times);
?>