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)

# https://atcoder.jp/contests/abc111/tasks/arc103_a

n = int(input())
v = list(map(int, input().split()))

f_l = v[::2]
s_l = v[1::2]


def count_and_sort(l):
    dict = {}
    for f in l:
        if f not in dict:
            dict[f] = 1
        else:
            dict[f] += 1
    return sorted(dict.items(), key=lambda x: -x[1])


f_sorted = count_and_sort(f_l)
s_sorted = count_and_sort(s_l)

f1 = f_sorted[0]
s1 = s_sorted[0]

f2 = f_sorted[1] if len(f_sorted) > 1 else (0, 0)
s2 = s_sorted[1] if len(s_sorted) > 1 else (0, 0)

if f1[0] == s1[0]:  # 同じ値だったら使えない
    print(min(n - f1[1] - s2[1], (n - f2[1] - s1[1])))
else:
    print(n - f1[1] - s1[1])