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)

N = int(input())
V =  [int(i) for i in input().split()]
V1 = [V[2*j-2] for j in range(1, N//2+1)]
V2 = [V[2*j-1] for j in range(1, N//2+1)]
#print(V1, V2)

def dict(x):
  D = {}
  for i in x:
    if i in D:
      D[i] += 1
    else:
      D.setdefault(i, 1)
  return D

dictV1 = dict(V1)
dictV2 = dict(V2)
#print(dictV1, dictV2)

sortdictV1 = sorted(dictV1.items(), key=lambda x:x[1], reverse=True)
sortdictV2 = sorted(dictV2.items(), key=lambda x:x[1], reverse=True)
a = 0
if sortdictV1[0][0] != sortdictV2[0][0]:
    a = N - sortdictV1[0][1] - sortdictV2[0][1]
else:
  if len(dictV1) == len(dictV2) == 1:
    a = N // 2
  else:
    if len(dictV1) == 1:
      a = N - sortdictV1[0][1] - sortdictV2[1][1]
    elif len(dictV2) == 1:
      a = N - sortdictV1[1][1] - sortdictV2[0][1]
    else:
      a = min(N - sortdictV1[0][1] - sortdictV2[1][1], N - sortdictV1[1][1] - sortdictV2[0][1])
print(a)