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: Time Limit Exceeded)

#!/usr/bin/ruby
# encoding: utf-8

# ABC 111 C

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

# vの要素がすべて同じ数字の時
if v.uniq.size == 1 then
  puts n/2
  exit
end 

# vの要素がすべて同じ数字ではないとき
modv = Array.new(n, -1)
ans = Array.new

k = 0
while k < n/2 do
  i = 0 
  while i < n/2 do
      modv[2*i] = v[2*k]
      modv[2*i+1] = v[2*k+1]
      i += 1
  end

  cnt = 0
  (0..n-1).each do |a|
    cnt += 1 if modv[a] != v[a]
  end
  ans.push(cnt)
  k += 1
end

p ans.min
#p modv