Problem: 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} ... s_{m} (1 ≤ m ≤ 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" → "baa" → "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 ≤ n ≤ 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

Solution (in PYTHON3):

Solution:
def clipher(s):
    res = [s[0]]

    for i, e in enumerate(s[1:]):
        if i % 2 == 0:
            res.append(e)
        else:
            res.insert(0, e)

    return res
        
def unclipher(s):
    res = [None] * len(s)
    indexes = clipher(list(range(len(s))))
    
    for i, e in enumerate(indexes):
        res[e] = s[i]
    
    return "".join(res)

def test(s):
    assert unclipher("".join(clipher(s))) == s

print(unclipher(input()))

#test("1234")