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)

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

array1 = v[::2]
array2 = v[1::2]

dict1 = {}
dict2 = {}
for i in array1:
  if i not in dict1:
    dict1[i] = 1
  else:
    dict1[i] = dict1[i] + 1

for i in array2:
  if i not in dict2:
    dict2[i] = 1
  else:
    dict2[i] = dict2[i] + 1

sort_array1 = []
sort_array2 = []
for k, v in sorted(dict1.items(), key=lambda x: -x[1]):
    sort_array1.append({k:v})
for k, v in sorted(dict2.items(), key=lambda x: -x[1]):
    sort_array2.append({k:v})

one_num1 = 0
one_num2 = 0

print (sort_array1)
print (sort_array2)

for k1,v1 in sort_array1[0].items():
  if len(sort_array1) != 1:
    one_num1 = len(array1) - v1
  for k2,v2 in sort_array2[0].items():
    if len(sort_array2) != 1:
      one_num2 = len(array2) - v2
    if k1 != k2:
      print(one_num1 + one_num2)
      break

    if len(sort_array1) == 1 and len(sort_array2) == 1:
      print(1)
      break
    if len(sort_array1) == 1:
      for k,v in sort_array2[1].items():
        two_num2 = v
      print(1+two_num2)
      break
    if len(sort_array2) == 1:
      for k,v in sort_array1[1].items():
        two_num1 = v
      print(1+two_num1)
      break

    for k,v in sort_array1[1].items():
      two_num1 = len(array1) - v
    for k,v in sort_array2[1].items():
      two_num2 = len(array2) - v
    if two_num1 <= two_num2:
      print (one_num2 + two_num1)
    else:
      print (one_num1 + two_num2)