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 Counter


def solve(V):
    n = len(V)
    odd = Counter()
    even = Counter()
    total = Counter()
    for i, c in enumerate(V):
        total.update([c])
        if i % 2 == 0:
            even.update([c])
        else:
            odd.update([c])

    total_max = total.most_common()[0]
    if total_max[1] == len(V):
        return len(V) / 2

    even_maxs = even.most_common(2)
    odd_maxs = odd.most_common(2)
    if len(odd_maxs) > 1:
        odd_max, odd_2nd_max = odd_maxs[0], odd_maxs[1]
    else:
        odd_max, odd_2nd_max = odd_maxs[0], None

    if len(even_maxs) > 1:
        even_max, even_2nd_max = even_maxs[0], even_maxs[1]
    else:
        even_max, even_2nd_max = even_maxs[0], None

    ans = 0
    if odd_max[0] != even_max[0]:
        odd_max = odd_max[0]
        even_max = even_max[0]
    elif odd_2nd_max != None and even_2nd_max == None:
        even_max = even_max[0]
        odd_max = odd_2nd_max[0]
    elif odd_2nd_max == None and even_2nd_max != None:
        odd_max = odd_max[0]
        even_max = even_2nd_max[0]
    else:  # odd_2nd_max != None and even_2nd_max != None:
        return n - max(even_maxs[0][1] + odd_maxs[1][1], 
                       even_maxs[1][1] + odd_maxs[0][1])

    for key, count in even.items():
        if key != even_max:
            ans += count
    for key, count in odd.items():
        if key != odd_max:
            ans += count
    return ans


if __name__ == "__main__":
    n = int(input())
    l = input()
    print(solve(l.split(" ")))