
# 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()))

print((1 if n == 0 else 0))


# optimized version of the same code:

n = int(eval(input()))

print((0 if n else 1))

n = int(eval(input()))
print((1 if n == 0 else 0))

n = int(eval(input()))
print((0 if n else 1))

-print((1 if n == 0 else 0)) +print((0 if n else 1))