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)

from collections import defaultdict

def getN():
    return int(input())

def getMN():
    a = input().split()
    b = [int(i) for i in a]
    return b[0],b[1]

def getlist():
    a = input().split()
    b = [int(i) for i in a]
    return b

n = getN()
nums = getlist()
lis1 = defaultdict(int)
lis2 = defaultdict(int)

for i,s in enumerate(nums):
    if i % 2 == 0:
        lis1[s] += 1
    else:
        lis2[s] += 1

maxk1 = []
maxv1 = 0
for k in lis1.keys():
    if lis1[k] == maxv1:
        maxk1.append(k)
    elif lis1[k] > maxv1:
        maxv1 = lis1[k]
        maxk1 = [k]

maxk2 = []
maxv2 = 0
for k in lis2.keys():
    if lis2[k] == maxv2:
        maxk2.append(k)
    elif lis2[k] > maxv2:
        maxv2 = lis2[k]
        maxk2 = [k]

v1 = list(lis1.values())
v1.sort(reverse=True)
v1 = v1 + [0]
v2 = list(lis2.values())
v2.sort(reverse=True)
v2 = v2 + [0]

if (len(maxk1) == 1) and (len(maxk2) == 1) and (maxk1[0] == maxk2[0]):
    if v1[0] >= v2[0]:
        ans = n - v1[0] -v2[1]
    else:
        ans = n- v2[0] - v1[1]

else:
    ans = n - maxv1 - maxv2
print(ans)