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

S = [eval(input()) for i in range(n)]

S.sort()

print(("".join(S)))

# optimized version of the same code:

n, l = list(map(int, input().split()))

A = [eval(input()) for _ in range(n)]

A.sort()

print(("".join(A)))

n, l = list(map(int, input().split()))
S = [eval(input()) for i in range(n)]
S.sort()
print(("".join(S)))

n, l = list(map(int, input().split()))
A = [eval(input()) for _ in range(n)]
A.sort()
print(("".join(A)))

-S = [eval(input()) for i in range(n)] -S.sort() -print(("".join(S))) +A = [eval(input()) for _ in range(n)] +A.sort() +print(("".join(A)))