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

v1 = []
v2 = []
n.times do |i|
  if i.even?
    v1.push(v[i])
  else
    v2.push(v[i])
  end
end

v11 = v1.group_by(&:to_i).sort_by{|_,v|-v.size}.map(&:first).first
v22 = v2.group_by(&:to_i).sort_by{|_,v|-v.size}.map(&:first).first

if v11 != v22
  p v1.count{|a| a != v11} + v2.count{|a| a != v22}
else
  v222 = v2.group_by(&:to_i).sort_by{|_,v|-v.size}.map(&:first)[1]
  tmp1 = v1.count{|a| a != v11} + v2.count{|a| a != v222}
  v111 = v1.group_by(&:to_i).sort_by{|_,v|-v.size}.map(&:first)[1]
  tmp2 = v1.count{|a| a != v111} + v2.count{|a| a != v22}
  p [tmp1, tmp2].min
end