
# 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 post_from_pre_in(preorder_elements, inorder_elements):

    if preorder_elements:

        global cnt

        root = preorder_elements[0]

        root_index = inorder_elements.index(root)

        preorder_left = preorder_elements[1:root_index+1]

        inorder_left = inorder_elements[:root_index]

        preorder_right = preorder_elements[root_index+1:]

        inorder_right = inorder_elements[root_index+1:]

        post_from_pre_in(preorder_left, inorder_left)

        post_from_pre_in(preorder_right, inorder_right)

        if cnt:

            print(root, end = ' ')

            cnt -= 1

        else:

            print(root)





cnt = int(input()) - 1



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

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



post_from_pre_in(a, b)


# optimized version of the same code:

postorder_elements = []



def post_from_pre_in(preorder_elements, inorder_elements):

    if preorder_elements:

        root = preorder_elements[0]

        root_index = inorder_elements.index(root)

        preorder_left = preorder_elements[1:root_index+1]

        inorder_left = inorder_elements[:root_index]

        preorder_right = preorder_elements[root_index+1:]

        inorder_right = inorder_elements[root_index+1:]

        post_from_pre_in(preorder_left, inorder_left)

        post_from_pre_in(preorder_right, inorder_right)

        postorder_elements.append(root)







n = int(eval(input()))



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

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



post_from_pre_in(a, b)



print((*postorder_elements))
def post_from_pre_in(preorder_elements, inorder_elements):
    if preorder_elements:
        global cnt
        root = preorder_elements[0]
        root_index = inorder_elements.index(root)
        preorder_left = preorder_elements[1 : root_index + 1]
        inorder_left = inorder_elements[:root_index]
        preorder_right = preorder_elements[root_index + 1 :]
        inorder_right = inorder_elements[root_index + 1 :]
        post_from_pre_in(preorder_left, inorder_left)
        post_from_pre_in(preorder_right, inorder_right)
        if cnt:
            print(root, end=" ")
            cnt -= 1
        else:
            print(root)


cnt = int(input()) - 1
a = list(map(int, input().split()))
b = list(map(int, input().split()))
post_from_pre_in(a, b)

postorder_elements = []


def post_from_pre_in(preorder_elements, inorder_elements):
    if preorder_elements:
        root = preorder_elements[0]
        root_index = inorder_elements.index(root)
        preorder_left = preorder_elements[1 : root_index + 1]
        inorder_left = inorder_elements[:root_index]
        preorder_right = preorder_elements[root_index + 1 :]
        inorder_right = inorder_elements[root_index + 1 :]
        post_from_pre_in(preorder_left, inorder_left)
        post_from_pre_in(preorder_right, inorder_right)
        postorder_elements.append(root)


n = int(eval(input()))
a = list(map(int, input().split()))
b = list(map(int, input().split()))
post_from_pre_in(a, b)
print((*postorder_elements))

+postorder_elements = [] + + -        global cnt -        if cnt: -            print(root, end=" ") -            cnt -= 1 -        else: -            print(root) +        postorder_elements.append(root) -cnt = int(input()) - 1 +n = int(eval(input())) +print((*postorder_elements))