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 = Hash.new(0)
b = Hash.new(0)
for i in 0..n/2-1
  a[v[i*2]] += 1
  b[v[i*2+1]] += 1
end
ans = n
a = a.sort_by{|k,v|v}
b = b.sort_by{|k,v|v}
if a[-1][0] != b[-1][0]
  ans -= a[-1][1]+b[-1][1]
elsif a.size == 1 && b.size == 1
  ans -= n/2
elsif a.size == 1
  ans -= a[-1][1]+b[-2][1]
elsif b.size == 1
  ans -= a[-2][1]+b[-1][1]
else
  ans -= a[-1][1] > b[-1][1] ? a[-1][1]+b[-2][1] : a[-2][1]+b[-1][1]
end
puts ans