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)

n = gets.to_i
vs = gets.split.map(&:to_i)
e = {}
o = {}
e1 = 0
e1v = nil
e2 = 0
e2v = nil
o1 = 0
o1v = nil
o2 = 0
o2v = nil
vs.each_with_index do |v, i|
  if i % 2 == 0
	e[v] = 0 unless e[v]
    e[v] += 1
    if e[v] > e1
      if v == e2v
        e2v = e1v
        e2 = e1
        e1v = v
        e1 = e[v]
      else
        e1v = v
        e1 = e[v]
      end
    elsif e[v] > e2
      e2 = e[v]
      e2v = v
    end
  else
	o[v] = 0 unless o[v]
    o[v] += 1
    if o[v] > o1
      if v == o2v
        o2v = o1v
        o2 = o1
        o1v = v
        o1 = o[v]
      else
        o1v = v
        o1 = o[v]
      end
    elsif o[v] > o2
      o2 = o[v]
      o2v = v
    end
  end
end
if e1v != o1v
  puts (n - e1 - o1)
else
  puts [ (n - e1 - o2), (n - e2 - o1)].min
end