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
v = gets.split.map(&:to_i)
odd = Hash.new(0)
div = Hash.new(0)

for i in 0..(N-1)
  if i % 2 == 0
    odd[v[i]] += 1
  else
    div[v[i]] += 1
  end
end

odds = Array.new(2, 0)
oddk = Array.new(2)
odd.each do |k, v|
  if odds[1] < v
    oddk[1] = k
    odds[1] = v
  end
  if odds[0] < odds[1]
    tmp = oddk[1]
    oddk[1] = oddk[0]
    oddk[0] = tmp
    tmp = odds[1]
    odds[1] = odds[0]
    odds[0] = tmp
  end
end

divs = Array.new(2, 0)
divk = Array.new(2)
div.each do |k, v|
  if divs[1] < v
    divk[1] = k
    divs[1] = v
  end
  if divs[0] < divs[1]
    tmp = divk[1]
    divk[1] = divk[0]
   divk[0] = tmp
    tmp = divs[1]
    divs[1] = divs[0]
    divs[0] = tmp
  end
end
  
if divk[0] != oddk[0]
  puts N - divs[0] - odds[0]
else
  if divs[0] > odds[0]
    puts N - divs[0] - odds[1]
  elsif divs[0] < odds[0]
    puts N - divs[1] - odds[0]
  else
    if divs[1] >= odds[1]
      puts N - divs[1] - odds[0]
    else
      puts N - divs[0] - odds[1]
    end
  end
end