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)

n = int(input().strip())
vs = list(map(int, input().split()))

def w2(x):
    return x[::2], x[1:][::2]

def isnnn(x):
    return len(set(x))==2 and len(set(x[::2]))==1 and len(set(x[1:][::2]))==1

def sa(v):
    vd = {}
    for i in v:
        if i in vd:
            vd[i] += 1
        else:
            vd[i] = 1
    max_k = max(vd, key=vd.get)
    return max_k, len(v) - vd[max_k], 

if isnnn(vs):
    print(0)
elif len(set(vs))==1:
    print(int(len(vs)/2))
else:
    v1, v2 = w2(vs)
    v1_k, sa1 = sa(v1)
    v2_k, sa2 = sa(v2)
    if v1_k != v2_k:
        print(sa1+sa2)
    elif sa1 < sa2:
        v1_s = list(filter(lambda x: x != v1_k, v1))
        v1_k2, sa12 = sa(v1_s)
        print(sa12+sa2+v1.count(v1_k))
    else:
        v2_s = list(filter(lambda x: x != v2_k, v2))
        v2_k2, sa22 = sa(v2_s)
        print(sa1+sa22+v2.count(v2_k))