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: Accepted)

# frozen_string_literal: true

n = gets.to_i
v = gets.split.map(&:to_i)

first = Hash.new(0)
second = Hash.new(0)
n.times do |i|
  if i.odd?
    first[v[i]] += 1
  else
    second[v[i]] += 1
  end
end

f1, f2 = first.sort_by { |_, v| -v }[0..1]
s1, s2 = second.sort_by { |_, v| -v }[0..1]
f2 = [200000, 0] if f2.nil?
s2 = [200000, 0] if s2.nil?

ans = if f1[0] == s1[0]
  if f1[1] - f2[1] < s1[1] - s2[1]
    n - f2[1] - s1[1]
  else
    n - f1[1] - s2[1]
  end
else
  n - f1[1] - s1[1]
end

puts ans