
# 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



s = input()[::-1]

length = len(s)

a = np.zeros(length, dtype=int)

d = np.zeros(length, dtype=int)

ans = np.zeros(2019, dtype=int)

x = 10



a[0] = int(s[0])

d[0] = a[0]

ans[d[0]] += 1



for i in range(1, length):

    a[i] = int(s[i]) * x % 2019

    d[i] = (d[i-1] + a[i]) % 2019

    ans[d[i]] += 1

    x = x * 10 % 2019



ans_c = ans[np.nonzero(ans)]



print((int(sum([ans_c[i] * (ans_c[i]-1) for i in range(ans_c.shape[0])]) / 2) + ans[0]))

# optimized version of the same code:

s = input()[::-1]

length = len(s)

a = [0] * length

d = [0] * length

ans = [0] * 2019

x = 10



a[0] = int(s[0])

d[0] = a[0]

ans[d[0]] += 1



for i in range(1, length):

    a[i] = int(s[i]) * x % 2019

    d[i] = (d[i-1] + a[i]) % 2019

    ans[d[i]] += 1

    x = x * 10 % 2019



print((int(sum([ans[i] * (ans[i]-1) for i in range(2019)]) / 2) + ans[0]))
import numpy as np

s = input()[::-1]
length = len(s)
a = np.zeros(length, dtype=int)
d = np.zeros(length, dtype=int)
ans = np.zeros(2019, dtype=int)
x = 10
a[0] = int(s[0])
d[0] = a[0]
ans[d[0]] += 1
for i in range(1, length):
    a[i] = int(s[i]) * x % 2019
    d[i] = (d[i - 1] + a[i]) % 2019
    ans[d[i]] += 1
    x = x * 10 % 2019
ans_c = ans[np.nonzero(ans)]
print(
    (int(sum([ans_c[i] * (ans_c[i] - 1) for i in range(ans_c.shape[0])]) / 2) + ans[0])
)

s = input()[::-1]
length = len(s)
a = [0] * length
d = [0] * length
ans = [0] * 2019
x = 10
a[0] = int(s[0])
d[0] = a[0]
ans[d[0]] += 1
for i in range(1, length):
    a[i] = int(s[i]) * x % 2019
    d[i] = (d[i - 1] + a[i]) % 2019
    ans[d[i]] += 1
    x = x * 10 % 2019
print((int(sum([ans[i] * (ans[i] - 1) for i in range(2019)]) / 2) + ans[0]))

-import numpy as np - -a = np.zeros(length, dtype=int) -d = np.zeros(length, dtype=int) -ans = np.zeros(2019, dtype=int) +a = [0] * length +d = [0] * length +ans = [0] * 2019 -ans_c = ans[np.nonzero(ans)] -print( -    (int(sum([ans_c[i] * (ans_c[i] - 1) for i in range(ans_c.shape[0])]) / 2) + ans[0]) -) +print((int(sum([ans[i] * (ans[i] - 1) for i in range(2019)]) / 2) + ans[0]))