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.chomp.split.map(&:to_i)
v1=[]
v2=[]

h1 = Hash.new(0)
h2 = Hash.new(0)
v.each_with_index do |w, i|
    if i%2==0
        v1 << w
        h1[w] += 1
    else
        v2 << w
        h2[w] += 1
    end
end

hh1 = h1.to_a.sort {|a,b| a[1] <=> b[1]}.reverse
hh2 = h2.to_a.sort {|a,b| a[1] <=> b[1]}.reverse

#p hh1
#p hh2
hh1 += [nil,0]
hh2 += [nil,0]

# 最頻値の数が同じ
if hh1[0][1] == hh2[0][1]
    # 最頻値の値も同じ
    if hh1[0][0] == hh2[0][0]
        # 最頻値の数がn/2（つまり全て同じ数値）
        if hh1[0][1] == n/2
            puts n/2
        else 
            puts n - hh1[0][1] - [hh1[1][1], hh2[1][1]].max
        end
    else
        puts n - 2 * hh1[0][1]
    end
else
    if hh1[0][0] == hh2[0][0]
        puts n - hh1[0][1] - [hh1[1][1], hh2[1][1]].max
    else
        puts n - hh1[0][1] - hh2[0][1]
    end
end