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 main () =
        let n = int_of_string (read_line ()) in
        let s, t = Scanf.scanf "%s %s" (fun s t -> s, t) in
        let rec loop i acc =
            if i = n then acc else loop (i + 1)
            (Printf.sprintf "%s%c%c" acc s.[i] t.[i])
        in
        loop 0 "" |> print_endline
    in
    main ()