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
[{"code": "n = int(input())\ns = input()\n\ni = 0\nto_add = 1\nwhile i < n:\n    print(s[i], end='')\n    i += to_add\n    to_add += 1\n", "passed": true, "time": 0.2, "memory": 14260.0, "status": "done"}, {"code": "n = int(input().strip())\ns = str(input().strip())\nc = 1\ni = 0\nwhile i < n:\n    print(s[i],end='')\n    i+=c\n    c+=1\n", "passed": true, "time": 0.23, "memory": 14036.0, "status": "done"}, {"code": "\n\nMOD = 10**9 + 7\nI = lambda:list(map(int,input().split()))\n\nn, = I()\ns = input()\nres = ''\ni = 0\nj = 2\nwhile i < n:\n    print(s[i], end='')\n    i += j\n    j += 1", "passed": true, "time": 0.24, "memory": 14256.0, "status": "done"}, {"code": "n = int(input())\nstring = input()\n\ni = 1\ncnt = 0\nwhile cnt < n:\n    print(string[cnt], end=\"\")\n\n    cnt += i\n    i += 1\n", "passed": true, "time": 0.21, "memory": 14352.0, "status": "done"}]