
# 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(list(map(int, input().split())))

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

p = v-c

ans = 0

for i in p:

    if i>0:

        ans+=i



print(ans)


# optimized version of the same code:

n=int(eval(input()))

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

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

ans=0

for v,c in zip(V,C):

    diff=v-c

    if 0<diff:

        ans+=diff

print(ans)
import numpy as np

n = int(eval(input()))
v = np.array(list(map(int, input().split())))
c = np.array(list(map(int, input().split())))
p = v - c
ans = 0
for i in p:
    if i > 0:
        ans += i
print(ans)

n = int(eval(input()))
V = list(map(int, input().split()))
C = list(map(int, input().split()))
ans = 0
for v, c in zip(V, C):
    diff = v - c
    if 0 < diff:
        ans += diff
print(ans)

-import numpy as np - -v = np.array(list(map(int, input().split()))) -c = np.array(list(map(int, input().split()))) -p = v - c +V = list(map(int, input().split())) +C = list(map(int, input().split())) -for i in p: -    if i > 0: -        ans += i +for v, c in zip(V, C): +    diff = v - c +    if 0 < diff: +        ans += diff