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: Time Limit Exceeded)

# coding: utf-8
# Your code here!
n = int(input())
v = list(map(int,input().split(" ")))
#print(v)


cnt = 0

#print(len(set(v)))
start = 0

while True:
    #print(v)
    
    if len(set(v)) == 1:
        cnt = n//2
        break
    
    flag = True#条件check用
    
    #print(v,start,n-2)
    for i in range(start,n-2):
        
        if v[i] != v[i+2]:
            v[i] = v[i+2]
            cnt += 1
            flag = False
            start = i
            
            break
    if flag and len(set(v)) == 2:
        break
    
    #cnt += 1
        
print(cnt)