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

e = Hash.new(0)
o = Hash.new(0)

n.times do |i|
  if i.even?
    e[v[i]] += 1
  else
    o[v[i]] += 1
  end
end

e.sort_by { |_,v| -v }
o.sort_by { |_,v| -v }

sube = (n/2) - e.values[0]
subo = (n/2) - o.values[0]

sube2 = e.length > 1 ? e.values[1] : 0
subo2 = o.length > 1 ? o.values[1] : 0

ans = 0
if e.keys[0] != o.keys[0]
  ans = sube+subo
else
  if sube2 > subo2
    ans = sube + ((n/2) - subo2)
  else
    ans = subo + ((n/2) - sube2)
  end
end

puts ans