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)

from collections import defaultdict
n = int(input())
nums = [int(each) for each in input().split()]
oddD = defaultdict(int)
evenD = defaultdict(int)
for i in range(len(nums)):
  if((i+1) % 2==0):
    evenD[nums[i]] += 1
  else:
    oddD[nums[i]] += 1
evenD_list = []
oddD_list = []
for key in evenD.keys():
  evenD_list.append([key, evenD[key]])
for key in oddD.keys():
  oddD_list.append([key,oddD[key]])
evenD_list.sort(key=lambda x :x[1])
oddD_list.sort(key=lambda x : x[1])
i = len(evenD_list)-1
j = len(oddD_list)-1
while(i > 0 and j > 0):
  e_value, e_num = evenD_list[i]
  o_value, o_num = oddD_list[j]
  if(e_value == o_value):
    if(e_num < o_num):
      i -= 1
    else:
      j -= 1
  else:
    break
if(i >= len(evenD_list)):
    i = len(evenD_list)-1
if(j >= len(oddD_list)):
    j = len(oddD_list)- 1
e_value, e_num = evenD_list[i]
o_value, o_num =oddD_list[j]
if(e_value == o_value):
  print(int((n/2-max(e_num,o_num) + n/2)))
else:
  print(int(n/2 - e_num + n/2 -o_num))