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)

import collections
N = int(input())
a = input().split( )

ret = [0]

odds = []
evens = []
for i in range(N):
    if i % 2 == 0:
        odds.append(int(a[i]))
    else:
        evens.append(int(a[i]))

codds = collections.Counter(odds)
cevens = collections.Counter(evens)

if codds.most_common()[0][0] ==cevens.most_common()[0][0]:
    if codds.most_common()[0][1] > cevens.most_common()[0][1]:
        codds = list(codds.values())
        cevens = list(cevens.values())
        if len(codds) > 1:
            codds=sorted(codds)
            codds.pop(-1)
        else:
            codds = [0]
        if len(cevens) > 1:
            cevens = sorted(cevens)
            cevens.pop(-2)
    else:
        codds = list(codds.values())
        cevens = list(cevens.values())
        if len(codds) > 1:
            codds=sorted(codds)
            codds.pop(-2)
        if len(cevens) > 1:
            cevens = sorted(cevens)
            cevens.pop(-1)
        else:
            cevens = [0]
else:
    codds = list(codds.values())
    cevens = list(cevens.values())
    if len(codds) > 1:
        codds=sorted(codds)
        codds.pop(-1)
    if len(cevens) > 1:
        cevens = sorted(cevens)
        cevens.pop(-1)

print(sum(codds) + sum(cevens))