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:
from math import *
from itertools import product
s = input()
s1 = ""
if len(s) == 1:
    print(s)
else:
    if len(s) % 2 == 0:
        s1 += s[len(s)//2 - 1]
        cnt = len(s)//2 - 2
        for i in range(len(s)//2, len(s)-1):
            s1 += s[i]
            s1 += s[cnt]
            cnt -= 1
        s1 += s[len(s) - 1]
    else:
        s1 += s[len(s) // 2]
        cnt = len(s) // 2 - 1
        for i in range(len(s) // 2 + 1, len(s)):
            s1 += s[i]
            s1 += s[cnt]
            cnt -= 1
print(s1)