
# 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:

import numpy as np

N = int(eval(input()))

Vlist = np.array(list(map(int,input().split())))

Clist = np.array(list(map(int,input().split())))



Dlist = Vlist-Clist



sum_ = 0

for d in Dlist:

    if d >= 0:

        sum_ += d



print(sum_)


# optimized version of the same code:

# 入力

N = int(eval(input()))

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

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



ans = 0

for i in range(N):

    Z = Vlist[i] - Clist[i]

    if Z > 0:

        ans += Z



print(ans)

import numpy as np

N = int(eval(input()))
Vlist = np.array(list(map(int, input().split())))
Clist = np.array(list(map(int, input().split())))
Dlist = Vlist - Clist
sum_ = 0
for d in Dlist:
    if d >= 0:
        sum_ += d
print(sum_)

# 入力
N = int(eval(input()))
Vlist = list(map(int, input().split()))
Clist = list(map(int, input().split()))
ans = 0
for i in range(N):
    Z = Vlist[i] - Clist[i]
    if Z > 0:
        ans += Z
print(ans)

-import numpy as np - +# 入力 -Vlist = np.array(list(map(int, input().split()))) -Clist = np.array(list(map(int, input().split()))) -Dlist = Vlist - Clist -sum_ = 0 -for d in Dlist: -    if d >= 0: -        sum_ += d -print(sum_) +Vlist = list(map(int, input().split())) +Clist = list(map(int, input().split())) +ans = 0 +for i in range(N): +    Z = Vlist[i] - Clist[i] +    if Z > 0: +        ans += Z +print(ans)