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 (3.8.2) (judge verdict: Accepted)

#!/usr/bin/env python3

#import
#import math
#import numpy as np
n = int(input())
V = list(map(int, input().split()))

even = {0:0}
odd = {0:0}

for i in range(n):
    v = V[i]
    if i % 2 == 0:
        if v in even:
            even[v] += 1
        else:
            even[v] = 1
    else:
        if v in odd:
            odd[v] += 1
        else:
            odd[v] = 1

omax = 0
emax = 0
onext = 0
enext = 0

for e in even:
    if even[e] > even[emax]:
        if even[emax] > even[enext]:
            enext = emax
        emax = e
    elif even[e] > even[enext]:
        enext = e

for o in odd:
    if odd[o] > odd[omax]:
        if odd[omax] > odd[onext]:
            onext = omax
        omax = o
    elif odd[o] > odd[onext]:
        onext = o

if omax != emax:
    print(n - even[emax] - odd[omax])
else:
    print(n - even[emax] - odd[omax] + min(even[emax] - even[enext], odd[omax] - odd[onext]))