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)

import itertools
from collections import Counter

N = int(input())
V = [int(x) for x in input().split()]
EV_counter = Counter(V[::2])
OD_counter = Counter(V[1::2])

# 1種類しかないとき対策
EV_counter[-1] = 0
OD_counter[-2] = 0

# 上位2種しか使う必要がない
EV = EV_counter.most_common(2)
OD = OD_counter.most_common(2)

answer = N
for (k1,v1), (k2,v2) in itertools.product(EV,OD):
  if k1 == k2:
    continue
  x = (N - v1 - v2)
  if answer > x:
    answer = x

print(answer)