
# 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

L = np.array(int(eval(input())), dtype='float128')

ans = (L / 3)**3

print(ans)


# optimized version of the same code:

import numpy as np

L = int(eval(input()))

ans = (L / 3)**3

print(ans)

import numpy as np

L = np.array(int(eval(input())), dtype="float128")
ans = (L / 3) ** 3
print(ans)

import numpy as np

L = int(eval(input()))
ans = (L / 3) ** 3
print(ans)

-L = np.array(int(eval(input())), dtype="float128") +L = int(eval(input()))