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 Python (3.4.3) (judge verdict: Wrong Answer)

import collections
n = int(input())

array = list(map(int, input().split()))
array_0 = collections.Counter(array[::2]).most_common()
array_1 = collections.Counter(array[1::2]).most_common()

array_0_v = array_0[0][0]
array_1_v = array_1[0][0]

if array_0_v == array_1_v:
    if array_0[0][1] > array_1[0][1]:
        if len(array_1) > 1:
            array_1_v = array_1[1][0]
        else:
            if array_0_v != 1:
                array_1_v = array_0_v - 1
            else:
                array_1_v = array_0_v + 1
    else:
        if len(array_0) > 1:
            array_0_v = array_0[1][0]
        else:
            if array_1_v != 1:
                array_0_v = array_1_v - 1
            else:
                array_0_v = array_1_v + 1
count = 0
for i in range(n // 2):
    if array[i * 2] != array_0_v:
        count += 1
    if array[i * 2 + 1] != array_1_v:
        count += 1

print(count)