
# 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 sys

import numpy as np



N = eval(input())



V = input().split()

v = np.array([ int(x) for x in V])



C = input().split()

c = np.array([ int(x) for x in C])



delt = v - c

print((delt[delt>0].sum()))

# 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):

    p = v - c

    if p > 0:

        ans += p



print(ans)

import sys
import numpy as np

N = eval(input())
V = input().split()
v = np.array([int(x) for x in V])
C = input().split()
c = np.array([int(x) for x in C])
delt = v - c
print((delt[delt > 0].sum()))

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):
    p = v - c
    if p > 0:
        ans += p
print(ans)

-import sys -import numpy as np - -N = eval(input()) -V = input().split() -v = np.array([int(x) for x in V]) -C = input().split() -c = np.array([int(x) for x in C]) -delt = v - c -print((delt[delt > 0].sum())) +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): +    p = v - c +    if p > 0: +        ans += p +print(ans)