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:
import math
wcipher = input()
center = math.ceil(len(wcipher)/2)
val = list(wcipher)
pos ={}
j = 0
out = ""
if len(wcipher)%2 == 0:
    start = len(wcipher)-1
else:
    start = len(wcipher)
for i in range(start, 0, -2):
    pos[i] = val[j]
    j = j +1
j = center
for i in range(2, len(wcipher)+1, 2):
    pos[i] = val[j]
    j = j +1
    
out = out.join('{}'.format(val) for key, val in sorted(pos.items()))
print(out)