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)

import sys
from collections import Counter

def defs(c1, c2):
    
    if c1[0][1] > c2[0][1]:
        return c1[0], c2[1]
    else:
        return c1[1], c2[0]

def main():
    input = sys.stdin.readline
    
    n = int(input())
    m = [int(i) for i in input().split()]
    
    even = [m[i] for i, _ in enumerate(m) if i % 2 == 0]
    odd = [m[i] for i, _ in enumerate(m) if i % 2 == 1]
    
    even_c = Counter(even).most_common()
    odd_c = Counter(odd).most_common()
    
    if even_c[0] == odd_c[0]:
        print(len(m) / 2)
        return
    
#    print(even_c)
#    print(odd_c)
    
    even_c, odd_c = defs(even_c, odd_c)
    
    if even_c[1] == odd_c[1]:
        ans = len(odd) - min(even_c[1], odd_c[1])
        
    else:
        ans = len(m) - (even_c[1] + odd_c[1])
    
    print(ans)


if __name__ == '__main__':
    main()