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: Accepted)

import collections

N = int(input())
V = list(map(int, input().split()))
odd = V[::2]
even = V[1::2]
odd_count =  collections.Counter(odd).most_common()
even_count = collections.Counter(even).most_common()

if odd_count[0] == even_count[0]:
  if len(odd_count) == 1:
    ans = N//2
  elif odd_count[1][1] == odd_count[0][1] or even_count[1][1] == even_count[0][1]:
    ans = N-(odd_count[0][1] + even_count[0][1])
  else:
    ans = N-max(odd_count[0][1] + even_count[1][1], odd_count[1][1]+ even_count[0][1])
else:
  ans = N-(odd_count[0][1] + even_count[0][1])

print(ans)