
# 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:

n = int(eval(input()))

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

#print(n,ary)



ary_2 = [ary[0]]

for i in range(1, n):

    ary_2.append(ary[i] + ary_2[i-1])

ary_2 = [0] + ary_2

#print(ary_2)



from collections import Counter

c = Counter(ary_2)

v = (list(c.values()))

#print(v)



from math import factorial

def combinations_count(n, r):

    return factorial(n) // (factorial(n - r) * factorial(r))



ans = 0

for j in v:

    if j >1:

        ans += combinations_count(j,2)



print(ans)

# optimized version of the same code:

n = int(eval(input()))

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

#print(n,ary)



ary_2 = [ary[0]]

for i in range(1, n):

    ary_2.append(ary[i] + ary_2[i-1])

ary_2 = [0] + ary_2

#print(ary_2)



from collections import Counter

c = Counter(ary_2)

v = (list(c.values()))

#print(v)



ans = 0

for j in v:

    if j >1:

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



print(ans)

n = int(eval(input()))
ary = list(map(int, input().split()))
# print(n,ary)
ary_2 = [ary[0]]
for i in range(1, n):
    ary_2.append(ary[i] + ary_2[i - 1])
ary_2 = [0] + ary_2
# print(ary_2)
from collections import Counter

c = Counter(ary_2)
v = list(c.values())
# print(v)
from math import factorial


def combinations_count(n, r):
    return factorial(n) // (factorial(n - r) * factorial(r))


ans = 0
for j in v:
    if j > 1:
        ans += combinations_count(j, 2)
print(ans)

n = int(eval(input()))
ary = list(map(int, input().split()))
# print(n,ary)
ary_2 = [ary[0]]
for i in range(1, n):
    ary_2.append(ary[i] + ary_2[i - 1])
ary_2 = [0] + ary_2
# print(ary_2)
from collections import Counter

c = Counter(ary_2)
v = list(c.values())
# print(v)
ans = 0
for j in v:
    if j > 1:
        ans += j * (j - 1) // 2
print(ans)

-from math import factorial - - -def combinations_count(n, r): -    return factorial(n) // (factorial(n - r) * factorial(r)) - - -        ans += combinations_count(j, 2) +        ans += j * (j - 1) // 2