
# 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=eval(input())

N=len(S)

mod=[0 for i in range(2019)]

mod2=0

ten=1

for i in range(N-1,-1,-1): 

  s=int(S[i])*ten

  mod2+=np.mod(s,2019)

  mod2=np.mod(mod2,2019)

  mod[mod2]+=1

  ten=(ten*10)%2019

ans=0

for i in range(2019):

  k=mod[i]

  if i==0:

    if k>=2:

      ans+=k*(k-1)//2+k

    else:

      ans+=k

  else:

    if k>=2:

      ans+=k*(k-1)//2

print(ans) 

# optimized version of the same code:

S=eval(input())

N=len(S)

mod=[0 for i in range(2019)]

s=0

ten=1

for i in range(N-1,-1,-1): 

  s+=int(S[i])*ten

  mod2=s%2019

  mod[mod2]+=1

  ten=(ten*10)%2019

ans=0

for i in range(2019):

  k=mod[i]

  if i==0:

    if k>=2:

      ans+=k*(k-1)//2+k

    else:

      ans+=k

  else:

    if k>=2:

      ans+=k*(k-1)//2

print(ans) 
import numpy as np

S = eval(input())
N = len(S)
mod = [0 for i in range(2019)]
mod2 = 0
ten = 1
for i in range(N - 1, -1, -1):
    s = int(S[i]) * ten
    mod2 += np.mod(s, 2019)
    mod2 = np.mod(mod2, 2019)
    mod[mod2] += 1
    ten = (ten * 10) % 2019
ans = 0
for i in range(2019):
    k = mod[i]
    if i == 0:
        if k >= 2:
            ans += k * (k - 1) // 2 + k
        else:
            ans += k
    else:
        if k >= 2:
            ans += k * (k - 1) // 2
print(ans)

S = eval(input())
N = len(S)
mod = [0 for i in range(2019)]
s = 0
ten = 1
for i in range(N - 1, -1, -1):
    s += int(S[i]) * ten
    mod2 = s % 2019
    mod[mod2] += 1
    ten = (ten * 10) % 2019
ans = 0
for i in range(2019):
    k = mod[i]
    if i == 0:
        if k >= 2:
            ans += k * (k - 1) // 2 + k
        else:
            ans += k
    else:
        if k >= 2:
            ans += k * (k - 1) // 2
print(ans)

-import numpy as np - -mod2 = 0 +s = 0 -    s = int(S[i]) * ten -    mod2 += np.mod(s, 2019) -    mod2 = np.mod(mod2, 2019) +    s += int(S[i]) * ten +    mod2 = s % 2019