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)

def main():
    n = int(input())
    v = list(map(int,input().split()))
    odd={}
    even={}
    for i in range(n):
        if i%2==0:
            if v[i] not in odd:
                odd[v[i]]=1
            else:
                odd[v[i]]+=1
        else:
            if v[i] not in even:
                even[v[i]]=1
            else:
                even[v[i]]+=1
    cnt_o=[]
    cnt_e=[]
    for i in odd:
        cnt_o.append([odd[i],i])
    for i in even:
        cnt_e.append([even[i],i])
    cnt_o.append([0,10**6])
    cnt_e.append([0,10**6])
    cnt_o.sort(reverse=True)
    cnt_e.sort(reverse=True)
    if cnt_o[0][1]!=cnt_e[0][1]:
        print(n-cnt_o[0][0]-cnt_e[0][0])
        return
    else:
        print(min(n-cnt_o[1][0]-cnt_e[0][0],n-cnt_o[0][0]-cnt_e[1][0]))
        return
if __name__ == "__main__":
    main()