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, m = map(int, input().split())
print(n + m)
'''
'''
n = int(input())
if n == 0:
    print(0)
else:
    a, b = 0, 1
    for i in range(2, n + 1):
        a, b = b, a + b
    print(b)
'''
'''
n, m = map(int, input().split())
print((n ** m) - (m ** n))
'''
'''
n = int(input())
print(n * 2 + 1)
'''
'''
a=int(input())
for i in range(1,a+1):
    if i%2!=0 and a>i:
        print('I hate that',end=' ')
    elif i%2==0 and a>i:
        print('I love that',end=' ')
    elif i%2!=0:
        print('I hate it',end=' ')
    else:
        print('I love it',end=' ')
'''
'''
a = int(input())
l = [[0] * a for i in range(a)]
a1 = []
for i in range(a):
    for j in range(a):
        if i == 0 :
            l[i][j] = 1
        else:
            l[i][j] =l[i - 1][j] + l[i][j -1]
for i in l:
    a1.append(max(i))
print(max(a1))
'''
'''
n = int(input())
cnt = 0
a = []
while n != 0:
	if n % 2 == 1:
		cnt += 1
		a.append(3)
		n -= 3
	else:
		cnt += 1
		a.append(2)
		n -= 2
print(cnt)
for i in a:
	print(i, end = " ")
print()
'''
'''
n = int(input())
t = False
kkk = []
for i in range(0,n):
    p = input().split('|')
    if t == False:
        for j in range(0,2):
            if p[j] == 'OO':
                p[j] = '++'
                t = True
                break
    kkk.append(p[0])
    kkk.append(p[1])
if t == False:
    print('NO')
else:
    print('YES')
    for i in range(0,n):
        print('|'.join(kkk[2*i:2*i+2]))
'''
'''
a=input()
b=list(map(int,input().split()))
c=0
for i in b:
    if b.count(i)>c:
        c=b.count(i)
print(c)
'''
'''
n = int(input())
for i in range(n):
    a, b, k = map(int,input().split())
    zero1 = k // 2
    if k % 2 == 0:
        zero2 = k // 2
    else:
        zero2 = (k // 2) + 1
    b *= zero1
    a *= zero2
    print(a - b)
'''
'''
n, m = map(int, input().split())
a = set(range(1, m + 1))
b = set()
for i in range(n):
	x, y = map(int, input().split())
	for i in range(x, y + 1):
		b.add(i)
for i in b:
	a.discard(i)
print(len(a))
for i in a:
	print(i, end = " ")
print()
'''
'''
n = int(input())
m = list(map(int,input().split()))
print(m.count(1))
for i in range(n - 1):
	if m[i + 1] == 1:
		print(m[i], end = ' ')
print(m[-1])
'''
'''
a = int(input())
l = list(map(int,input().split()))
k = 1
for i in range(a - 1):
    l2 = list(map(int,input().split()))
    if sum(l2) > sum(l):
        k += 1
print(k)
'''
'''
n=int(input())
a=input()
c=0
for i in range(n-2):
    if a[i]+a[i+1]+a[i+2]=="xxx":
        c+=1
print(c)
'''
'''
n = input()
s = ''
for i in range(len(n)):
	if n[i] == '0':
		s += '1'
	else:
		s += '0'
print(s)
'''
a = int(input())
m = input()
k = 0
i = - 1
while k != a:
	i += 1
	print(m[k] , end = "") 
	k += i + 1