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)

#!/usr/bin/env ruby
n = STDIN.readline.strip.to_i
v = STDIN.readline.strip.split(' ').map(&:to_i)
o = {}
e = {}
for i in 0..(n/2-1) do
  e[v[i*2]] = e[v[i*2]].nil? ? 1 : e[v[i*2]]+1
  o[v[i*2+1]] = o[v[i*2+1]].nil? ? 1 : o[v[i*2+1]]+1
end
e_s = e.sort_by{|k, v| v}
o_s = o.sort_by{|k, v| v}
if e_s.length == 1 and o_s.length == 1 and e_s[0][0] == o_s[0][0]
  e_n = 0
  o_n = o_s[0][1]
elsif e_s.length == 1 and o_s.length != 1
  e_n = e_s[0][1]
  o_n = o_s[1][1]
elsif e_s.length != 1 and o_s.length == 1
  e_n = e_s[1][1]
  o_n = o_s[0][1]
elsif e_s[0][0] == o_s[0][0]
  e0o1 = e_s[0][1] + o_s[1][1]
  e1o0 = e_s[1][1] + o_s[0][1]
  if e0o1 >= e1o0
    e_n = e_s[0][1]
    o_n = o_s[1][1]
  else
    e_n = e_s[1][1]
    o_n = o_s[0][1]
  end
else
  e_n = e_s[0][1]
  o_n = o_s[0][1]
end
puts n - (e_n + o_n)