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 main():
    n = int(input())
    v_n = input().split(' ')
    
    guusuu = Counter(v_n[::2])
    kisuu = Counter(v_n[1::2])

    guusuu = guusuu.most_common()
    kisuu = kisuu.most_common()

    if len(set(guusuu)) == 1:
        # 偶数番目１種類
        print(n//2 - kisuu[0][1])
    elif len(set(kisuu)) == 1:
        # 奇数番目１種類
        print(n//2 - guusuu[0][1])
    # ２種類以上
    elif guusuu[0][0] == kisuu[0][0]:
        # 最頻値が同じ時，どちらがは譲らないといけない
        # => ２番目の最頻値で書き換えるべき
        result = min(n - guusuu[0][1] - kisuu[1][1], n- guusuu[1][1] - kisuu[0][1])
        print(result)
    else:
        # 最頻値が違う時，どちらも最頻値で書き換え
        print(n - guusuu[0][1] - kisuu[0][1])
    





main()