
# 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:

s=int(eval(input()))

p=10**9+7

if s<=2:

    print((0))

    exit()

n=s//3

ans=0

def f(n,k,p):

    if k==0:

        return 1

    elif k%2==0:

        return (f(n,k//2,p)**2)%p

    else:

        return (n*f(n,k-1,p))%p



for k in range(1,n+1):

    a=1

    b=1

    for j in range(k-1):

        a=(a*(s-3*k+1+j))%p

        b=(b*(j+1))%p

    ans=(ans+a*f(b,p-2,p))%p



print((ans%p))




# optimized version of the same code:

s=int(eval(input()))

p=10**9+7

if s<=2:

    print((0))

    exit()

n=s//3

ans=0

x=[0]*(s+1)

x[0]=1

x[1]=1

y=[0]*(s+1)



for i in range(2,s+1):

    x[i]=x[i-1]*i%p



y[s]=pow(x[s],p-2,p)

for i in range(s):

    y[s-1-i]=y[s-i]*(s-i)%p



for k in range(1,n+1):

    ans+=x[s-2*k-1]*y[k-1]*y[s-3*k]%p



print((ans%p))



s = int(eval(input()))
p = 10**9 + 7
if s <= 2:
    print((0))
    exit()
n = s // 3
ans = 0


def f(n, k, p):
    if k == 0:
        return 1
    elif k % 2 == 0:
        return (f(n, k // 2, p) ** 2) % p
    else:
        return (n * f(n, k - 1, p)) % p


for k in range(1, n + 1):
    a = 1
    b = 1
    for j in range(k - 1):
        a = (a * (s - 3 * k + 1 + j)) % p
        b = (b * (j + 1)) % p
    ans = (ans + a * f(b, p - 2, p)) % p
print((ans % p))

s = int(eval(input()))
p = 10**9 + 7
if s <= 2:
    print((0))
    exit()
n = s // 3
ans = 0
x = [0] * (s + 1)
x[0] = 1
x[1] = 1
y = [0] * (s + 1)
for i in range(2, s + 1):
    x[i] = x[i - 1] * i % p
y[s] = pow(x[s], p - 2, p)
for i in range(s):
    y[s - 1 - i] = y[s - i] * (s - i) % p
for k in range(1, n + 1):
    ans += x[s - 2 * k - 1] * y[k - 1] * y[s - 3 * k] % p
print((ans % p))

- - -def f(n, k, p): -    if k == 0: -        return 1 -    elif k % 2 == 0: -        return (f(n, k // 2, p) ** 2) % p -    else: -        return (n * f(n, k - 1, p)) % p - - +x = [0] * (s + 1) +x[0] = 1 +x[1] = 1 +y = [0] * (s + 1) +for i in range(2, s + 1): +    x[i] = x[i - 1] * i % p +y[s] = pow(x[s], p - 2, p) +for i in range(s): +    y[s - 1 - i] = y[s - i] * (s - i) % p -    a = 1 -    b = 1 -    for j in range(k - 1): -        a = (a * (s - 3 * k + 1 + j)) % p -        b = (b * (j + 1)) % p -    ans = (ans + a * f(b, p - 2, p)) % p +    ans += x[s - 2 * k - 1] * y[k - 1] * y[s - 3 * k] % p