Problem:
Score : 200 points

Problem Statement

Given are strings s and t of length N each, both consisting of lowercase English letters.

Let us form a new string by alternating the characters of S and the characters of T, as follows: the first character of S, the first character of T, the second character of S, the second character of T, ..., the N-th character of S, the N-th character of T. Print this new string.

Constraints

1 \leq N \leq 100

|S| = |T| = N

S and T are strings consisting of lowercase English letters.

Input

Input is given from Standard Input in the following format:

N
S T

Output

Print the string formed.

Sample Input 1

2
ip cc

Sample Output 1

icpc

Sample Input 2

8
hmhmnknk uuuuuuuu

Sample Output 2

humuhumunukunuku

Sample Input 3

5
aaaaa aaaaa

Sample Output 3

aaaaaaaaaa

Solution in Common Lisp (SBCL 1.1.14) (judge verdict: Accepted)

(defun split (x str)
  (let ((pos (search x str))
        (size (length x)))
    (if pos
      (cons (subseq str 0 pos)
            (split x (subseq str (+ pos size))))
      (list str))))

(defparameter N (parse-integer (read-line)))
(defparameter lst (split " " (read-line)))

(defparameter *my-string* (make-array 0
                                      :element-type 'character
                                      :fill-pointer 0
                                      :adjustable t))

(loop for i from 0 below N do
      (vector-push-extend (char (car lst) i) *my-string*)
      (vector-push-extend (char (cadr lst) i) *my-string*))

(format t "~A" *my-string*)