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())
V = list(map(int, input().split()))

V_e = V[1::2]
V_o = V[::2]

dic_e = collections.Counter(V_e)
dic_o = collections.Counter(V_o)

e12 = []
for k,v in dic_e.items():
    e12.append((k,v))
o12 = []
for k,v in dic_o.items():
    o12.append((k,v))

if e12 == o12:
    ans = n//2
elif e12[0][0] != o12[0][0]:
    ans = (n//2 - e12[0][1]) + (n//2 - o12[0][1])
else:
    if e12[0][1] > o12[0][1]:
        ans = (n//2) - e12[0][1]
        if e12[0][0] == o12[0][0]:
            ans += (n//2) - o12[1][1]
        else:
            ans += (n//2) - o12[0][1]
    elif e12[0][1] < o12[0][1]:
        ans = (n//2) - o12[0][1]
        if e12[0][0] == o12[0][0]:
            ans += (n//2) - e12[1][1]
        else:
            ans += (n//2) - e12[0][1]
    else:
        if e12[1][1] >= o12[1][1]:
            ans = (n//2 - e12[1][1]) + (n//2 - o12[0][1])
        elif e12[1][1] < o12[1][1]:
            ans = (n//2 - e12[0][1]) + (n//2 - o12[1][1])

print(ans)