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 Ruby (2.3.3) (judge verdict: Wrong Answer)

n = gets.to_i
n + 1

raw_array = gets.chomp.split(' ').map(&:to_i)
 
even_count = 0
even_array = []
even_hash = {}
even_indiv_numbers = []
odd_count = 0
odd_array = []
odd_hash = {}
odd_indiv_numbers = []
 
raw_array.each_with_index do |item, idx|
  if idx % 2 == 0
    even_array << item
    even_count += 1
    if even_indiv_numbers.include?(item)
      even_hash[item.to_s] += 1
    else
      even_indiv_numbers << item
      even_hash[item.to_s] = 1
    end
  else
    odd_array << item
    odd_count += 1
    if odd_indiv_numbers.include?(item)
      odd_hash[item.to_s] += 1
    else
      odd_indiv_numbers << item
      odd_hash[item.to_s] = 1
    end
  end
end

even_count -= even_hash.values.max
odd_count -= odd_hash.values.max

result = even_count + odd_count

if even_array == odd_array
  result = even_array.length
end

puts result