
# slower version:

s = input()
for i in range(len(s)):
  if i%2 == 0:
    print(s[i], end = '')


# optimized version of the same code:

s = input()
ans = ''
for i in range(len(s)):
  if i % 2 == 0:
    ans += s[i]
print(ans)



# slower version:

def main():

    N = int(input())

    A = [int(i) for i in input().split()]

    if N == 1:

        return print(1 if A[0] % 2 == 0 else 2)

    ans = 0

    d = (-1, 0, 1)

    from itertools import product

    for i in product(range(3), repeat=N):

        cur = 1

        for j in range(N):

            cur *= (A[j] + d[i[j]])

        if cur % 2 == 0:

            ans += 1

    print(ans)





if __name__ == '__main__':

    main()


# optimized version of the same code:

def main():

    N = int(eval(input()))

    A = [int(i) for i in input().split()]

    ans = 3**N

    cnt = len([a for a in A if a % 2 == 0])

    ans -= 2**cnt

    print(ans)





if __name__ == '__main__':

    main()

def main():
    N = int(input())
    A = [int(i) for i in input().split()]
    if N == 1:
        return print(1 if A[0] % 2 == 0 else 2)
    ans = 0
    d = (-1, 0, 1)
    from itertools import product

    for i in product(range(3), repeat=N):
        cur = 1
        for j in range(N):
            cur *= A[j] + d[i[j]]
        if cur % 2 == 0:
            ans += 1
    print(ans)


if __name__ == "__main__":
    main()

def main():
    N = int(eval(input()))
    A = [int(i) for i in input().split()]
    ans = 3**N
    cnt = len([a for a in A if a % 2 == 0])
    ans -= 2**cnt
    print(ans)


if __name__ == "__main__":
    main()

-    N = int(input()) +    N = int(eval(input())) -    if N == 1: -        return print(1 if A[0] % 2 == 0 else 2) -    ans = 0 -    d = (-1, 0, 1) -    from itertools import product - -    for i in product(range(3), repeat=N): -        cur = 1 -        for j in range(N): -            cur *= A[j] + d[i[j]] -        if cur % 2 == 0: -            ans += 1 +    ans = 3**N +    cnt = len([a for a in A if a % 2 == 0]) +    ans -= 2**cnt