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 Perl (v5.18.2) (judge verdict: Wrong Answer)

$N = <STDIN>;
@A = split(" ",<STDIN>);
@a_odd = ();
@a_even = ();
for(my $i = 0; $i < $#A + 1; $i++){
	if($i%2 == 0){
		push @a_even,$A[$i];
    }
    else{
		push @a_odd,$A[$i];
    }
}
sub mode_sort{
	my @list = @_;
    my %dup_hash;
    my @out_list;
    my @out_keys;
    for my $number(@list){
    	$dup_hash{$number}++;
    }
    
    for my $key (sort {$dup_hash{$b} <=> $dup_hash{$a}} keys %dup_hash) {
		push @out_list,$dup_hash{$key};
        push @out_keys,$key;
    }
    return (@out_keys,@out_list);
}

my @odd = &mode_sort(@a_odd);
my @even = &mode_sort(@a_even);

if($odd[0] != $even[0]){

    $first = $N/2 - $odd[($#odd+1)/2] + $N/2 - $even[($#odd+1)/2];
	print $first;
    exit(0);
}
else{

    $first = $N/2 - $odd[($#odd+1)/2+1] +$N/2 - $even[($#odd+1)/2];
    $second = $N/2 - $odd[($#odd+1)/2] +$N/2 - $even[($#odd+1)/2+1];
    if($first <= $second){
    	print $first;
        exit(0);
    }
    else{
    	print $second;
        exit(0);
    }
}