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)

;; B - Strings with the Same Length

(defun main ()
  (let* ((N (read))
         (row (read-line))
         (SS (subseq row 0 N))
         (ST (subseq row (1+ N))))
    (princ (interleave SS ST))))

(defun interleave (s1 s2)
  (apply #'concatenate 'string
    (mapcar #'(lambda (ls) (coerce ls 'string))
      (map 'list #'list s1 s2))))

(main)