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
from itertools import takewhile

n = int(input())
vvv = list(map(int, input().split()))
cnt1 = Counter(vvv[0::2])
cnt2 = Counter(vvv[1::2])
mc1 = cnt1.most_common()
mc2 = cnt2.most_common()
mcs1 = list(takewhile(lambda x: x[1] == mc1[0][1], mc1))
mcs2 = list(takewhile(lambda x: x[1] == mc2[0][1], mc2))
print(mc1, mc2, mcs1, mcs2)
if len(mcs1) == len(mcs2) and mcs1[0][0] == mcs2[0][0]:
    if len(mc1) > 1:
        if len(mc2) > 1:
            print(min(n - mc1[0][1] - mc2[1][1], n - mc1[1][1] - mc2[0][1]))
        else:
            print(min(n - mc1[0][1], n - mc1[1][1] - mc2[0][1]))
    else:
        if len(mc2) > 1:
            print(min(n - mc1[0][1] - mc2[1][1], n - mc2[0][1]))
        else:
            print(min(n - mc1[0][1], n - mc2[0][1]))
else:
    print(n - mc1[0][1] - mc2[0][1])