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 solve (a b)
  (cons (car a)
        (cons (car b)
              (if (or (null (cdr a)) 
                      (null (cdr b)))
                  nil
                  (solve (cdr a) (cdr b))))))

(let* ((n (read))
       (str (read-line))
       (a (coerce (subseq str 0 n) 'list))
       (b (coerce (subseq str (+ n 1)) 'list)))
  (princ (coerce (solve a b) 'string)))