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: Runtime Error)

from collections import Counter
N = int (input())
List = list(map(int, input().split()))
List_even = List[0::2]
List_odd = List[1::2]
e1 = Counter(List_even)
o1 = Counter(List_odd)

e1_v = e1.most_common(1)
e1_atai = e1_v[0][0]
e1_kosuu = e1_v[0][1]

o1_v = o1.most_common(1)
o1_atai = o1_v[0][0]
o1_kosuu = o1_v[0][1]

if List_even == List_odd:
    print (len(List_odd))
else:
    if e1_atai != o1_atai:
        count_e = len(List_even) - e1_kosuu
        count_o = len(List_odd) - o1_kosuu
        print (count_e + count_o)
    
    else:
        e2 = Counter(List_even.remove(e1_atai))
        o2 = Counter(List_odd.remove(o1_atai))
        e2_v = e2.most_common(1)
        e2_atai = e2_v[0][0]
        e2_kosuu = e2_v[0][1]
        o2_v = o2.most_common(1)
        o2_atai = o2_v[0][0]
        o2_kosuu = o2_v[0][1]
        if e1_kosuu > o1_kosuu:
            count_e = len(List_even) - e1_kosuu
            count_o = len(List_odd) - o2_kosuu
            print (count_e + count_o)
        elif o1_kosuu > e1_kosuu:
            count_e = len(List_even) - e2_kosuu
            count_o = len(List_odd) - o1_kosuu
            print (count_e + count_o)
        else:
            if e2_kosuu > o2_kosuu:
                count_e = len(List_even) - e2_kosuu
                count_o = len(List_odd) - o1_kosuu
                print (count_e + count_o)
            if o2_kosuu >= e2_kosuu:
                count_e = len(List_even) - e1_kosuu
                count_o = len(List_odd) - o2_kosuu
                print (count_e + count_o)