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

odd_vsc = Hash.new(0)
even_vsc = Hash.new(0)
gets.split.map(&:to_i).each_with_index do |v, i|
  if i.odd?
    odd_vsc[v.to_s] += 1
  else
    even_vsc[v.to_s] += 1
  end
end

odd_vsc = odd_vsc.sort { |(k1, v1), (k2, v2)| v2 <=> v1 }
even_vsc = even_vsc.sort { |(k1, v1), (k2, v2)| v2 <=> v1 }

odd_c = 0
even_c = 0
odd_key, odd_value = odd_vsc[0]
even_key, even_value = even_vsc[0]

if odd_key == even_key
  if odd_value == even_value
    odd_c = n / 2
    even_c = 0
  elsif odd_value > even_value
    odd_c = n / 2 - odd_value
    even_c = n / 2 - even_vsc[1]
  else
    even_c = n / 2 - even_value
    odd_c = n / 2 - odd_vsc[1] 
  end
else
  odd_c = n / 2 - odd_value
  even_c = n / 2 - even_value
end

puts odd_c + even_c