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: Accepted)

from collections import Counter
n=int(input())
v=list(map(int,input().split()))
E=[0]*(n//2)
O=[0]*(n//2)
for i in range(n):
    if i%2==0:
        O[i//2]=v[i]
    else:
        E[i//2]=v[i]
cntE=Counter(E)
cntO=Counter(O)
if cntE.most_common()[0][0]!=cntO.most_common()[0][0]:
    print(n-cntE.most_common()[0][1]-cntO.most_common()[0][1])
else:
    if len(cntE.most_common())==1 and len(cntO.most_common())==1:
        print(n//2)
    elif len(cntE.most_common())==1:
        print(n-cntE.most_common()[0][1]-cntO.most_common()[1][1])
    elif len(cntO.most_common())==1:
        print(n-cntE.most_common()[1][1]-cntO.most_common()[0][1])
    else:
        print(min(n-cntE.most_common()[0][1]-cntO.most_common()[1][1],n-cntE.most_common()[1][1]-cntO.most_common()[0][1]))