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 = input()
V = list(map(int, input().split(" ")))

"""
9
1 1 1 1 2 2 2 4 
1 1 1 1 3 3 4 4
"""

#V = [1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 2, 3, 2, 4, 4, 4]

v1 = V[0::2]
v2 = V[1::2]

f1 = Counter(v1).most_common(2)
f2 = Counter(v2).most_common(2)

ans = 0

if len(set(v1)) == len(set(v2)) == 1:
    if v1 == v2:
        ans = min(len(v1), len(v2))
else:
    if f1[0][0] != f2[0][0]:
        ans = (len(v1) - f1[0][1]) + (len(v2) - f2[0][1])
    else:
        if f1[1][1] < f2[1][1]:
            ans = (len(v1) - f1[0][1]) + (len(v2) - f2[1][1])
        else:
            ans = (len(v1) - f1[1][1]) + (len(v2) - f2[0][1])
        
print(ans)