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
vs = gets.strip.split(/ /).collect{|item| item.to_i}

v1 = {}
v2 = {}

def put(table, v)
	if num = table[v]
		table[v] = num + 1
	else
		table[v] = 1
	end
end

(n / 2).times{|i|
	put(v1, vs[i * 2])
	put(v2, vs[i * 2 + 1])
}

v1 = v1.to_a.sort_by{|n, count| -count}
v2 = v2.to_a.sort_by{|n, count| -count}

if v1[0][0] != v2[0][0]
	puts n - v1[0][1] - v2[0][1]
else
	if v1.length > 1 && v2.length > 1
		x1 = v1[0][1] + v2[1][1]
		x2 = v1[1][1] + v2[0][1]
		puts n - [x1, x2].max
	elsif v1.length == 1 && v2.length == 1
		puts n / 2
	elsif v1.length == 1
		puts n - v2[1][1]
	else
		puts n - v1[1][1]
	end
end