
# 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:

def popcount(x):

  r = 0

  while x:

    if x & 1:

      r += 1

    x >>= 1

  return r



n = int(eval(input()))

r = list(range(n))

a = [[0, 0] for _ in r]

for i in r:

  for _ in range(int(eval(input()))):

    x, y = list(map(int, input().split()))

    a[i][y] |= 1 << (x - 1)



m = 0

l = (1 << n) - 1

for x in range(1, l + 1):

  if all(a[i][0] & x == a[i][1] & l - x == 0 for i in r if x >> i & 1):

    m = max(m, popcount(x))

print(m)


# optimized version of the same code:

from itertools import combinations

 

n = int(eval(input()))

r = list(range(n))

a = [(set(), set()) for _ in r]

for i in r:

  for _ in range(int(eval(input()))):

    x, y = list(map(int, input().split()))

    a[i][y].add(x - 1)

 

fail = lambda x: not all(a[i][0].isdisjoint(x) and a[i][1] < x for i in x)

 

while all(map(fail, list(map(set, combinations(r, n))))):

  n -= 1

print(n)
def popcount(x):
    r = 0
    while x:
        if x & 1:
            r += 1
        x >>= 1
    return r


n = int(eval(input()))
r = list(range(n))
a = [[0, 0] for _ in r]
for i in r:
    for _ in range(int(eval(input()))):
        x, y = list(map(int, input().split()))
        a[i][y] |= 1 << (x - 1)
m = 0
l = (1 << n) - 1
for x in range(1, l + 1):
    if all(a[i][0] & x == a[i][1] & l - x == 0 for i in r if x >> i & 1):
        m = max(m, popcount(x))
print(m)

from itertools import combinations

n = int(eval(input()))
r = list(range(n))
a = [(set(), set()) for _ in r]
for i in r:
    for _ in range(int(eval(input()))):
        x, y = list(map(int, input().split()))
        a[i][y].add(x - 1)
fail = lambda x: not all(a[i][0].isdisjoint(x) and a[i][1] < x for i in x)
while all(map(fail, list(map(set, combinations(r, n))))):
    n -= 1
print(n)

-def popcount(x): -    r = 0 -    while x: -        if x & 1: -            r += 1 -        x >>= 1 -    return r - +from itertools import combinations -a = [[0, 0] for _ in r] +a = [(set(), set()) for _ in r] -        a[i][y] |= 1 << (x - 1) -m = 0 -l = (1 << n) - 1 -for x in range(1, l + 1): -    if all(a[i][0] & x == a[i][1] & l - x == 0 for i in r if x >> i & 1): -        m = max(m, popcount(x)) -print(m) +        a[i][y].add(x - 1) +fail = lambda x: not all(a[i][0].isdisjoint(x) and a[i][1] < x for i in x) +while all(map(fail, list(map(set, combinations(r, n))))): +    n -= 1 +print(n)