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 bisect import bisect_right as br
from bisect import bisect_left as bl
from collections import defaultdict
from itertools import combinations
import functools
import sys
import math
MAX = sys.maxsize
MAXN = 10**6+10
MOD = 10**9+7
def isprime(n):
    n = abs(int(n))
    if n < 2:
        return False
    if n == 2: 
        return True    
    if not n & 1: 
        return False
    for x in range(3, int(n**0.5) + 1, 2):
        if n % x == 0:
            return False
    return True

def mhd(a,b,x,y):
    return abs(a-x)+abs(b-y)

def numIN():
    return(map(int,sys.stdin.readline().strip().split()))

def charIN():
    return(sys.stdin.readline().strip().split())

t = [(-1,-1)]*1000010

def create(a):
	global t,n
	for i in range(n,2*n):
		t[i] = (a[i-n],i-n)
	for i in range(n-1,0,-1):
		x = [t[2*i],t[2*i+1]]
		x.sort(key = lambda x:x[0])
		t[i] = x[1]

def update(idx,value):
	global t,n
	idx = idx+n
	t[idx] = value

	while(idx>1):
		idx = idx//2
		x = [t[2*idx],t[2*idx+1]]
		x.sort(key = lambda x:x[0])
		t[idx] = x[1]


def cal(n,k):
	res = 1
	c = [0]*(k+1)
	c[0]=1
	for i in range(1,n+1):
	    for j in range(min(i,k),0,-1):
	        c[j] = (c[j]+c[j-1])%MOD
	return c[k]


i = 0
n = int(input())
s = input()
j = 1
while i<n:
	print(s[i],end='')
	i+=j
	j+=1