
# 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()))

V = np.array([int(i) for i in input().split(" ")])

C = np.array([int(i) for i in input().split(" ")])



vc = V-C



val = 0



for i in range(N):

    if vc[i]>0:

        val+=vc[i]

print(val)

# optimized version of the same code:

N = int(eval(input()))

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

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



val = 0



for i in range(N):

    vc=V[i]-C[i]

    if vc>0:

        val+=vc

print(val)
import numpy as np

N = int(eval(input()))
V = np.array([int(i) for i in input().split(" ")])
C = np.array([int(i) for i in input().split(" ")])
vc = V - C
val = 0
for i in range(N):
    if vc[i] > 0:
        val += vc[i]
print(val)

N = int(eval(input()))
V = [int(i) for i in input().split(" ")]
C = [int(i) for i in input().split(" ")]
val = 0
for i in range(N):
    vc = V[i] - C[i]
    if vc > 0:
        val += vc
print(val)

-import numpy as np - -V = np.array([int(i) for i in input().split(" ")]) -C = np.array([int(i) for i in input().split(" ")]) -vc = V - C +V = [int(i) for i in input().split(" ")] +C = [int(i) for i in input().split(" ")] -    if vc[i] > 0: -        val += vc[i] +    vc = V[i] - C[i] +    if vc > 0: +        val += vc