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)

# 2019-11-10 17:11:42(JST)
import sys
import collections
# import math
# from string import ascii_lowercase, ascii_uppercase, digits
# from bisect import bisect_left as bi_l, bisect_right as bi_r
# import itertools
# from functools import reduce
import operator as op
# from scipy.misc import comb # float
# import numpy as np
# import statistics

def main():
    
    n, *v = (int(x) for x in sys.stdin.read().split())

    odds, evens = [], []
    for i in range(n):
        if i % 2 == 0:
            odds.append(v[i])
        else:
            evens.append(v[i])


    o_c = collections.Counter(odds)
    e_c = collections.Counter(evens)
    
    o_c = sorted(list((k, v) for k, v in o_c.items()), key=op.itemgetter(1), reverse=True)
    e_c = sorted(list((k, v) for k, v in e_c.items()), key=op.itemgetter(1), reverse=True)

    ans = n
    if o_c[0][0] != e_c[0][0]:
        ans = n - o_c[0][1] - e_c[0][1]
    else:
        if len(o_c) == 1 and len(e_c) == 1:
            ans = n - n // 2
        elif len(o_c) == 1 and len(e_c) >= 2:
            ans = n - e_c[1][1]
        elif len(o_c) >= 2 and len(e_c) == 1:
            ans = n - o_c[1][1]
        else:
            ans = n - max(o_c[0][1] + e_c[1][1], o_c[1][1] + e_c[0][1])
    
    print(ans)

if __name__ == "__main__":
    main()