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())
v = list(map(int, input().split()))
v1 = Counter(v[::2])
v2 = Counter(v[::-2])
if len(Counter(v))==1:
    print(N//2)
elif (len(v1)==1) and (len(v2)==1):
    print(0)
elif (len(v1)==1):
    k,v = zip(*v2.most_common())
    print(sum(v[1:]))
elif (len(v2)==1):
    k,v = zip(*v1.most_common())
    print(sum(v[1:]))
else:
    k1,v1 = zip(*v1.most_common())
    k2,v2 = zip(*v2.most_common())
    if k1[0]==k2[0]:
        if k1[0] >= k2[0]:
            print(sum(v1[1:])+v2[0]+(sum(v2[2:]) if len(v2)>2 else 0))
        else:
            print(sum(v2[1:])+v1[0]+(sum(v1[2:]) if len(v1)>2 else 0))
    else:
        print(sum(v1[1:])+sum(v2[1:]))