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 Common Lisp (SBCL 1.1.14) (judge verdict: Runtime Error)

(let* ((n (read))
       (lst-a nil)
       (lst-b nil))
  (loop :for k :from 1 :upto n
        :if (oddp k)
          :do(push (read) lst-a)
        :else
          :do (push (read) lst-b))
  (sort lst-a #'<)
  (sort lst-b #'<)
  (setf lst-a (compressor lst-a))
  (setf lst-b (compressor lst-b))
  (labels ((f (a b)
             (if (and (and a b) (not (= (car a) (car b))))
                 (+ (- (/ n 2) (cdr a))
                    (- (/ n 2) (cdr b)))
                 most-positive-fixnum)))
    (let* ((ans (min (f (first lst-a) (first lst-b))
                     (f (first lst-a) (second lst-b))
                     (f (second lst-a) (first lst-b))
                     (f (second lst-a) (second lst-b)))))
      (if (= most-positive-fixnum ans)
          (princ (/ n 2))
          (princ ans)))))