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)

def GetMaxes(d):
    m = []
    for k, v in d.items():
        m.append([k,v])
    m.sort(key=lambda x:-x[1])

    if len(m) == 1:
        m.append([0, 0])
    return m[:2]

def main():
    n = int(input())
    v = list(map(int, input().split()))

    dic0 = dict()
    dic1 = dict()
    d = [dic0, dic1]
    for i in range(n):
        dic = d[i%2]
        if v[i] not in dic:
            dic[v[i]] = 1
        else:
            dic[v[i]] += 1

    m0 = GetMaxes(d[0])
    m1 = GetMaxes(d[1])

    if m0[0][0] == m1[0][0]:
        take0 = m0[0][1] + m1[1][1]
        take1 = m1[0][1] + m0[1][1]
        if take0 > take1:
            print(n-take0)
        else:
            print(n-take1)
    else:
        print(n - m0[0][1] - m1[0][1])

if __name__ == "__main__":
    main()