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())
v = list(map(int, input().split()))
if len(set(v)) == 1:
  print(0)
  exit()
ov = [v[i] for i in range(1,len(v),2)]
ev = [v[i] for i in range(0, len(v), 2)]

cov = collections.Counter(ov)
cev = collections.Counter(ev)
mov = cov.most_common()[0][0]
mev = cev.most_common()[0][0]
ans = len(v) - cov[mov] - cev[mev]

if mov == mev:
  ans1 = len(v) - cov.most_common()[1][1] - cev.most_common()[0][1]
  ans2 = len(v) - cov.most_common()[0][1] - cev.most_common()[1][1]
  ans = min(ans1, ans2)

print(ans)