Problem: Polycarp is mad about coding, that is why he writes Sveta encoded messages. He calls the median letter in a word the letter which is in the middle of the word. If the word's length is even, the median letter is the left of the two middle letters. In the following examples, the median letter is highlighted: contest, info. If the word consists of single letter, then according to above definition this letter is the median letter. 

Polycarp encodes each word in the following way: he writes down the median letter of the word, then deletes it and repeats the process until there are no letters left. For example, he encodes the word volga as logva.

You are given an encoding s of some word, your task is to decode it. 

Input

The first line contains a positive integer n (1 ≤ n ≤ 2000) — the length of the encoded word.

The second line contains the string s of length n consisting of lowercase English letters — the encoding.

Output

Print the word that Polycarp encoded.

Examples

Input

5
logva


Output

volga


Input

2
no


Output

no


Input

4
abba


Output

baba

Note

In the first example Polycarp encoded the word volga. At first, he wrote down the letter l from the position 3, after that his word looked like voga. After that Polycarp wrote down the letter o from the position 2, his word became vga. Then Polycarp wrote down the letter g which was at the second position, the word became va. Then he wrote down the letter v, then the letter a. Thus, the encoding looked like logva.

In the second example Polycarp encoded the word no. He wrote down the letter n, the word became o, and he wrote down the letter o. Thus, in this example, the word and its encoding are the same.

In the third example Polycarp encoded the word baba. At first, he wrote down the letter a, which was at the position 2, after that the word looked like bba. Then he wrote down the letter b, which was at the position 2, his word looked like ba. After that he wrote down the letter b, which was at the position 1, the word looked like a, and he wrote down that letter a. Thus, the encoding is abba.

Solution (in PYTHON3):

Solution:
'''
# CodeForce Equalize Prices 900 points

# a = old price / b = new price / k =value input
def Computer_Game():

    for _ in range(int(input())):
        k, n, a, b = map(int, input().split())  # init charge, num turns in game, a,b bat value
        max_turns=0
        for turns in range(n):

            if k/b > n and (k-a)/b < n-1 and turns == 0:
                max_turns=0
                break
            else:
                if k > a:
                    k -= a
                    max_turns += 1
                elif k > b:
                    k -= b
                    if k/b == n-turns:
                        max_turns = 1
                        break
                else:
                    max_turns = -1
                    break


        print(max_turns)


    return


def bit_plus_plus():

    summe = 0
    for _ in range(int(input())):

        statement = input()
        if '+' in statement:
            summe += 1
        else:
            summe -= 1
    print(summe)
    return

def petya_and_strings():

    str_a, str_b = input().lower(), input().lower()
    a=(str_a<str_b)
    print((str_a>str_b)-(str_a<str_b))


    return




def beautiful_matrix():

    for idx in range(5):

        row_input = list(map(int,input().split()))
        if 1 in row_input:
            row = idx+1
            for idx1, elem in enumerate(row_input):
                if elem == 1:
                    column = idx1+1

    output = abs(3 - row) + abs(3 - column)
    print(output)
        #for row_num in range(4):
           # if 1 in row(row_num)

    return


def helpful_maths():


    string = sorted(list(input().split('+')))
    print('+'.join(string))

    return


def word_capitalization():

    string = input()
    string_new = string[0].upper()+string[1:]
    print(string_new)

    return

def Stones_on_the_Table():
    _ = input()
    string=list(input())
    color_old = ''
    color_old_old = ''
    take = 0
    for color in string:

        if color == color_old:
            take += 1
        else:
            color_old = color


    print(take)

    return

def Boy_or_girl():
    print([{*input()}])
    string = input()
    new_string = ''
    for _ in string:
        if _ not in new_string:
            new_string = new_string + _
    if len(new_string) % 2 != 0:
        print('IGNORE HIM!')
    else:
        print('CHAT WITH HER!')

    return


def soldier_and_bananas():

    k,n,w = map(int,input().split())
    prize = 0
    for num in range(w):
        prize = prize + (num+1)*k

    print(prize-n if prize-n > 0 else 0)
    return


def bear_and_big_brother():

    a,b = map(int, input().split())
    years = 0
    while a <= b:
        a = a*3
        b = b*2
        years += 1

    print(years)

    return


def Tram():
    passenger = []
    cur_pass = 0
    for _ in range(int(input())):

        exit_passenger, enter_passenger = map(int,input().split())
        cur_pass = cur_pass - exit_passenger + enter_passenger
        passenger.append(cur_pass)

    print(max(passenger))
    return



def subtract_one(number):

    if float(number)%10 == 0:
        result = number / 10
    else:
        result = number - 1

    return int(result)

def wrong_subtraction():

    n, k = map(int, input().split())

    for _ in range(k):
        n = subtract_one(n)

    print(n)
    return

def wet_shark_and_odd_and_even():

    odd = []
    even = []
    odd_cnt = 0
    n = input()
    numbers = list(map(int,input().split()))
    for number in numbers:
        if number%2 == 0:
            even.append(number)
        else:
            odd.append(number)
            odd_cnt += 1

    odd.sort()
    k = int(odd_cnt/2)*2
    if k > 0:
        summe = sum(even) + sum(odd[-k:])
    else:
        summe = sum(even)
    print(summe)


    return





def sorting(volumes):

    sorting_steps = 0
    idx = 0
    cnt = 0
    while(idx < len(volumes)-1):
        a = volumes[idx]
        b = volumes[idx+1]
        # print(volumes)
        if a > b:
            volumes[idx] = b
            volumes[idx+1] = a
            sorting_steps += 1
            if idx > 0:
                idx -= 1

            else:
                cnt = cnt+1
                idx = cnt

        else:
            idx += 1
    return sorting_steps

def cubes_sorting():

    for _ in range(int(input())):

        n = int(input())
        a = list(map(int,input().split()))

        max_sort = n*(n-1)/2-1

        sorting_steps = sorting(a)

        if sorting_steps > max_sort:
            print('NO')
        else:
            print('YES')


    return

def elephant():

    coord = int(input())
    steps_taken = 0
    for steps in range(5,0,-1):
        if (coord / steps) >= 1:
            steps_taken = int(coord / steps) + steps_taken
            coord = int(coord % steps)
    print(steps_taken)
    return

def queue_at_the_school():
    number, time = map(int,input().split())
    queue=list(input())

    i = 0

    while i < time:
        idx = 0
        while idx < len(queue)-1:
            if queue[idx] == 'B' and queue[idx+1] == 'G':
                queue[idx] = 'G'
                queue[idx+1] = 'B'
                idx += 2
            else:
                idx += 1
        i += 1

    print(''.join(queue))
    return

def nearly_lucky_number():
    number = input()
    l_number = 0
    bla=[sum(i in '47' for i in number) in [4, 7]]
    print('4' in number)
    for elem in number:
        if elem == '7' or elem == '4':
            l_number += 1
    print('YES' if l_number == 4 or l_number == 7 else 'NO')

    return

def word():
    string = input()
    count = 0
    for elem in string:
        if elem.isupper():
            count += 1

    print(string.upper() if count > len(string)/2 else string.lower())

    return
'''
def translation():
    word_1 = input()
    word_2 = input()[::-1]
    print(["NO", "YES"] [word_1 == word_2])


    return

def anton_and_danik():

    games = int(input())
    wins=input()
    anton_wins = sum(i == 'A' for i in wins)
    if anton_wins*2 > len(wins):
        print('Anton')
    elif anton_wins*2 == len(wins):
        print('Friendship')
    else:
        print('Danik')
    return

def acoomodation():

    cnt = 0
    for _ in range(int(input())):
        p, q = map(int, input().split())
        if q - p >= 2:
            cnt +=1

    print(cnt)


    return

def juicer():

    n, b, d = map(int, input().split())

    sum_orange = 0
    cnt_empty = 0
    for orange in list(map(int, input().split())):

        if orange <= b:
            sum_orange += orange
            if sum_orange > d:
                cnt_empty += 1
                sum_orange = 0
    print(cnt_empty)
    return


def digit_game():

    for game in range(int(input())):
        breach_odd_cnt = 0
        breach_even_cnt = 0
        raze_odd_cnt = 0
        raze_even_cnt = 0
        n = int(input())
        number = input()
        breach_numbers = ''
        raze_numbers = ''
        len_number = len(number)

        idx = 1
        for digit in number:

            if idx%2 == 0:
                breach_numbers += digit
                if digit in '13579':
                    breach_odd_cnt += 1
                else:
                    breach_even_cnt += 1
            else:
                raze_numbers += digit
                if digit in '13579':
                    raze_odd_cnt += 1
                else:
                    raze_even_cnt += 1
            idx += 1
        if len_number == 1:
            if int(number)%2 == 0:
                print(2)
            else:
                print(1)
        elif len_number%2 == 0:  # last pick from raze raze lässt eins übrig
            if breach_even_cnt >= 1:
                print(2)
            else:
                print(1)
        else:  # last pick from breach breach lässt übrig
            if raze_odd_cnt >= 1:
                print(1)
            else:
                print(2)

            # raze only odd breach only even 1 = odd 0 = even raze starts
            # 1 raze wins
            # 2 breach wins

    return

def modular_exponentiation():

    n = int(input())
    m = int(input())
    #print(int((0b1 << n)))
    calc = m % int((0b1 << n))
    print(int(calc))

    return

def tricky_sum():


    for _ in range(int(input())):

        number = int(input())

        pow_two = 1
        while pow_two <= number:

            pow_two *= 2 #pow_two + int(pow_two << 1)
            print(pow_two)
            #print(pow_two)




        sum_formula = number*(number+1)//2
        trick_sum = sum_formula - 2*pow_two+2
        print(trick_sum)
    return

def three_indices():

    for _ in range(int(input())):
        n = int(input())

        permutation = list(map(int, input().split()))

        idx_i, idx_j, idx_k = 1 , 2 , 3
        num_i, num_j, num_k = 0, 0, 0

        for idx in range(1,n-1):
            if(permutation[idx]>permutation[idx-1] and permutation[idx] > permutation[idx+1]):
                print('YES')
                print(idx,idx+1,idx+2)
                break

        else:
            print('NO')




        #i,j,k

    return
def three_friends():

    for test_cases in range(int(input())):

        coords = list(map(int, input().split()))
        coords_neu = sorted(coords)



        if coords_neu[2] - coords_neu[0] <= 2:
            print(0)
        else:
            print(2*(coords_neu[2] - coords_neu[0])-4)
    return


def decoding():

    length = int(input())
    word = list(input())
    new_word = ''

    for i in range(1, length+1, 1):

        if len(word) % 2 != 0:
            new_word = new_word + word[0]
        else:
            new_word = word[0] + new_word

        word.pop(0)

    print(new_word)


    return
if __name__ == '__main__':

    decoding()

'''
if __name__ == '__main__':
    num_queries = int(input())

    for querie in range(num_queries):
        num_products, value_products = map(int, input().split())
        price_products = list(map(int, input().split()))
        B_Max = min(price_products)+value_products
        B_Min = max(price_products)-value_products
        if B_Max >= B_Min:
            print(B_Max)
        else:
            print(-1)
'''