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)
a=[]
b=[]
(n/2).times do |i|
  a<<v[2*i]
  b<<v[2*i+1]
end
if v.uniq.count == 1
  puts '2'
else
  mode_a=a.max_by{|x| a.count(x)}
  mode_b=b.max_by{|x| b.count(x)}
  if mode_a == mode_b
    aa = a.reject{|x| x == mode_a}
    bb = b.reject{|x| x == mode_b}
    temp_a = aa.max_by{|x| aa.count(x)}
    temp_b = bb.max_by{|x| bb.count(x)}
    if aa.count(temp_a) <= bb.count(temp_b)
      mode_a = temp_a
    else
      mode_b = temp_b
    end
  end
  puts n - a.count(mode_a) - b.count(mode_b)
end