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)

from collections import Counter

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

list_o = list[::2]
list_e = list[1::2]

cnt_o = Counter(list_o).most_common(2)
cnt_e = Counter(list_e).most_common(2)

#最頻値が同じ
if cnt_o[0][0] == cnt_e[0][0]:
    #値が1つ
    if len(cnt_o) == 1 and len(cnt_e) ==1:
        print(int(len(list) / 2))
    elif len(cnt_o) == 1 and len(cnt_e) != 1:
        print(len(list) - cnt_o[0][1] - cnt_e[1][1])
    elif len(cnt_o) != 1 and len(cnt_e) == 1:
        print(len(list) - cnt_o[0][1] - cnt_e[1][1])
    else:
        print(min(len(list) - cnt_o[1][1] - cnt_e[0][1], len(list) - cnt_o[0][1] - cnt_e[1][1]))
#最頻値が異なる
elif cnt_o[0][0] != cnt_e[0][0]:
    if len(cnt_o) == 1 and len(cnt_e) ==1:
        print(0)
    else:
        print(len(list) - cnt_o[0][1] - cnt_e[0][1])