A. Repeating Cipher
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

Polycarp loves ciphers. He has invented his own cipher called repeating.

Repeating cipher is used for strings. To encrypt the string $s=s_{1}s_{2} \dots s_{m}$ ($1 \le m \le 10$), Polycarp uses the following algorithm:

• he writes down $s_1$ ones,
• he writes down $s_2$ twice,
• he writes down $s_3$ three times,
• ...
• he writes down $s_m$ $m$ times.

For example, if $s$="bab" the process is: "b" $\to$ "baa" $\to$ "baabbb". So the encrypted $s$="bab" is "baabbb".

Given string $t$ — the result of encryption of some string $s$. Your task is to decrypt it, i. e. find the string $s$.

Input

The first line contains integer $n$ ($1 \le n \le 55$) — the length of the encrypted string. The second line of the input contains $t$ — the result of encryption of some string $s$. It contains only lowercase Latin letters. The length of $t$ is exactly $n$.

It is guaranteed that the answer to the test exists.

Output

Print such string $s$ that after encryption it equals $t$.

Examples
Input
6
baabbb

Output
bab
Input
10
ooopppssss

Output
oops
Input
1
z

Output
z