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())
num_list = input().split()
m=1
num_list_1 = []
num_list_2 = []
for n in range(0, n, 2):
    num_list_1.append(num_list[n])
    num_list_2.append(num_list[n+1])
c_1 = collections.Counter(num_list_1)
c_2 = collections.Counter(num_list_2)

lib_1 = c_1.most_common()
lib_2 = c_2.most_common()
k = 0

z = len(lib_1)
for n in range(1,z):
    k += int(lib_1[n][1])

z = len(lib_2)
for n in range(1,z):
    k += int(lib_2[n][1])
    
if lib_1[0][0] != lib_2[0][0]:
    print(k)
else:
    if lib_1[0][1] >= lib_2[0][1]:
        print(k+lib_2[0][1])
    else:
        print(k+lib_1[0][1])