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:
n = int(input().strip())
text = input().strip()


def root(n:int)->int:
  disc:int = 1+4*2*n;
  return  (-1 + int( disc**(1/2) ))//2;

storage = [0]*(root(n))



"""
token = ''
t_length = 0

for i in text:
  if token!=i:
    storage[t_length]=i
    t_length = 0
  
  token=i;
  t_length+=1
"""

token = ''
t_length = 0

for i in range(len(storage)):
  storage[i] = text[t_length]
  t_length = t_length+i+1

print(''.join(storage))