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)

import collections

n=int(input())
m=n//2
a=list(map(int,input().split()))
g=[]
k=[]
for x in range(n):
  if (x+1)%2==1:
    k.append(a[x])
  else:
    g.append(a[x])
    
gg=collections.Counter(g)
kk=collections.Counter(k)
aa=collections.Counter(a)

if len(aa)==1:
  print(n//2)
  
else:
  if gg.most_common()[0]==kk.most_common()[0]:
    if len(gg)>1 and len(kk)>1:
      print(min(m-gg.most_common()[0][1]+m-kk.most_common()[1][1],m-kk.most_common()[0][1]+m-gg.most_common()[1][1]))
    elif len(gg)==1:
      print(m-kk.most_common()[1][1])
    else:
      print(m-gg.most_common()[1][1])
  else:
    print(n-gg.most_common()[0][1]-kk.most_common()[0][1])