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
N = int(input())
A = list(map(int, input().split()))
c1 = Counter(A[::2])
c2 = Counter(A[1::2])
c1m = sorted(c1.items(), key=lambda x:x[1])
c2m = sorted(c2.items(), key=lambda x:x[1])
tmp = N - c1m[0][1] - c2m[0][1]
if tmp == 0:
    if c1m[0][0] == c2m[0][0]:
        print(N // 2)
        exit()
else:
    if c1m[0][0] == c2m[0][0]:
        len_c1m = len(c1m)
        len_c2m = len(c2m)
        if c1m[0][1] == c2m[0][1]:
            if c1m[1][1] > c2m[1][1]:
                print(N - c2m[0][1] - c1m[1][1])
                exit()
            else:
                print(N - c1m[0][1] - c2m[1][1])
                exit()
print(tmp)