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())
n = N // 2

index = 0
g_inputs = []
k_inputs = []

for i in input().split():
    if index % 2 == 0:
        g_inputs.append(int(i))
        index += 1
    else:
        k_inputs.append(int(i))
        index += 1

g = Counter(g_inputs)
k = Counter(k_inputs)

g_max = max([(v,k) for k,v in g.items()])[1] 
k_max = max([(v,k) for k,v in k.items()])[1]

if g_max == k_max:
    if g[g_max] < k[k_max]:
        del g[g_max]
        g_max = max([(v,k) for k,v in g.items()])[1]
        print(N - g[g_max] - k[k_max])
    if g[g_max] > k[k_max]:
        del k[k_max]
        k_max = max([(v,k) for k,v in k.items()])[1]
        print(N - g[g_max] - k[k_max])
    else:
        del g[g_max]
        del k[k_max]
        if len(g) == 0 and len(k) == 0:
            print(n)
        if len(g) != 0 and len(k) == 0:
            print(n - g_max - max([(v,k) for k,v in g.items()])[1])
        if len(g) == 0 and len(k) != 0:
            print(n - k_max - max([(v,k) for k,v in k.items()])[1])
        if len(g) != 0 and len(k) != 0:
            g_temp = g_max
            k_temp = k_max
            g_max = max([(v,k) for k,v in g.items()])[1]
            k_max = max([(v,k) for k,v in k.items()])[1]
            if g[g_max] < k[k_max]:
                print(n - k[k_max])
            elif g[g_max] > k[k_max]:
                print(n - g[g_max])
            else:
                print(N - g[g_max] - k[k_max])
else:
    print(N - g[g_max] - k[k_max])