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: Wrong Answer)

import sys
input = sys.stdin.readline
from collections import defaultdict

def main():
	n = int(input().strip())
	v = list(map(int, input().strip().split()))
	ki = defaultdict(int)
	gu = defaultdict(int)
	for i in range(n):
		if i % 2 == 0:
			gu[v[i]] += 1
		else:
			ki[v[i]] += 1
	km = 0
	kmi = 0
	ksm = 0
	ksmi = 0
	gm = 0
	gsm = 0
	gmi = 0
	gsmi = 0
	for k, v in ki.items():
		if v > km:
			km = v
			kmi = k
	for k, v in ki.items():
		if k == kmi:
			continue
		if v > ksm:
			ksm = v
			ksmi = k

	for k, v in gu.items():
		if v > gm:
			gm = v
			gmi = k
	for k, v in gu.items():
		if k == gmi:
			continue
		if v > gsm:
			gsm = v
			gsmi = k
	ks = sum(ki.values()) - km
	gs = sum(gu.values()) - gm
	if kmi == gmi:
		if km < gm:
			ks = ks - ksm + km
		else:
			gs = gs - gsm + gm
	print(ks + gs)
	return 0

if __name__ == '__main__':
	main()