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 OCaml (4.02.3) (judge verdict: Accepted)

let () =
  let n, s, t = Scanf.scanf "%d\n%s %s\n" @@ fun a b c -> a, b, c in
  let ans = Array.make (n*2) 'x' in
  for i = 0 to n-1 do
    ans.(2*i) <- s.[i]; ans.(2*i+1) <- t.[i];
  done;
  print_endline (Array.fold_left (fun s a -> s ^ Char.escaped a) "" ans)