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 PyPy3 (2.4.0) (judge verdict: Accepted)

from collections import defaultdict
n = int(input())
v = list(map(int, input().split()))
even = [[0,i] for i in range(10**5+5)]
odd = [[0,i] for i in range(10**5+5)]
numnum = 0
for i in range(n):
    if even[v[i]][0] == 0 and odd[v[i]][0] == 0:
        numnum += 1
    if i % 2 == 0:
        even[v[i]][0] += 1
    else:
        odd[v[i]][0] += 1
if numnum == 1:
    print(n // 2)
    exit()
even.sort(key=lambda x:x[0], reverse=True)
odd.sort(key=lambda x:x[0], reverse=True)
if n == 2:
    print(0)
    exit()
e0, e1, o0, o1 = even[0][1], even[1][1], odd[0][1], odd[1][1]
if e0 != o0:
    print(n - even[0][0] - odd[0][0])
elif e0 != o1 and e1 != o0:
    print(min(n - even[0][0] - odd[1][0], n - even[1][0] - odd[0][0]))
elif e0 != o1:
    print(n - even[0][0] - odd[1][0])
else:
    print(n - even[1][0] - odd[0][0])