
# 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:

from sys import stdin

from math import factorial





def combinations_count(n, r):

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





def combinations_with_replacement_count(n, r):

    return combinations_count(n + r - 1, r)





def main():

    _in = [_.rstrip() for _ in stdin.readlines()]

    S = int(_in[0])  # type:int

    # vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

    min_ = 1

    max_ = S // 3

    ans = 0

    for i in range(min_, max_ + 1):

        mod = S - i * 3

        ans += combinations_with_replacement_count(mod + 1, i - 1) % (10**9 + 7)

    ans %= (10**9 + 7)

    # ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    print(ans)





if __name__ == "__main__":

    main()


# optimized version of the same code:

from sys import stdin





class ModComb():

    def __init__(self, n_max, mod):

        self.fac = None

        self.mod = mod

        self.make_fac_table(n_max)



    def make_fac_table(self, n_max):

        self.fac = [1] + [0] * n_max

        for i in range(1, n_max + 1):

            self.fac[i] = self.fac[i - 1] * i % self.mod



    def mod_comb(self, n, k):

        if n == 0 and k == 0:

            return 1

        elif n < k or k < 0:

            return 0

        else:

            return self.fac[n] * pow(self.fac[n - k], self.mod - 2, self.mod) * \

                pow(self.fac[k], self.mod - 2, self.mod) % self.mod



    def mod_comb_with_rep(self, n, k):

        return self.mod_comb(n + k - 1, k)





def main():

    _in = [_.rstrip() for _ in stdin.readlines()]

    S = int(_in[0])  # type:int

    # vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

    ans = 0

    MOD = 10**9 + 7

    modcomb = ModComb(S + 1, MOD)

    min_ = 1

    max_ = S // 3

    for i in range(min_, max_ + 1):

        res = S - i * 3

        ans += modcomb.mod_comb_with_rep(res + 1, i - 1)

        ans %= MOD

    # ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    print(ans)





if __name__ == "__main__":

    main()

from sys import stdin
from math import factorial


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


def combinations_with_replacement_count(n, r):
    return combinations_count(n + r - 1, r)


def main():
    _in = [_.rstrip() for _ in stdin.readlines()]
    S = int(_in[0])  # type:int
    # vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
    min_ = 1
    max_ = S // 3
    ans = 0
    for i in range(min_, max_ + 1):
        mod = S - i * 3
        ans += combinations_with_replacement_count(mod + 1, i - 1) % (10**9 + 7)
    ans %= 10**9 + 7
    # ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    print(ans)


if __name__ == "__main__":
    main()

from sys import stdin


class ModComb:
    def __init__(self, n_max, mod):
        self.fac = None
        self.mod = mod
        self.make_fac_table(n_max)

    def make_fac_table(self, n_max):
        self.fac = [1] + [0] * n_max
        for i in range(1, n_max + 1):
            self.fac[i] = self.fac[i - 1] * i % self.mod

    def mod_comb(self, n, k):
        if n == 0 and k == 0:
            return 1
        elif n < k or k < 0:
            return 0
        else:
            return (
                self.fac[n]
                * pow(self.fac[n - k], self.mod - 2, self.mod)
                * pow(self.fac[k], self.mod - 2, self.mod)
                % self.mod
            )

    def mod_comb_with_rep(self, n, k):
        return self.mod_comb(n + k - 1, k)


def main():
    _in = [_.rstrip() for _ in stdin.readlines()]
    S = int(_in[0])  # type:int
    # vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
    ans = 0
    MOD = 10**9 + 7
    modcomb = ModComb(S + 1, MOD)
    min_ = 1
    max_ = S // 3
    for i in range(min_, max_ + 1):
        res = S - i * 3
        ans += modcomb.mod_comb_with_rep(res + 1, i - 1)
        ans %= MOD
    # ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    print(ans)


if __name__ == "__main__":
    main()

-from math import factorial -def combinations_count(n, r): -    return factorial(n) // (factorial(n - r) * factorial(r)) +class ModComb: +    def __init__(self, n_max, mod): +        self.fac = None +        self.mod = mod +        self.make_fac_table(n_max) +    def make_fac_table(self, n_max): +        self.fac = [1] + [0] * n_max +        for i in range(1, n_max + 1): +            self.fac[i] = self.fac[i - 1] * i % self.mod -def combinations_with_replacement_count(n, r): -    return combinations_count(n + r - 1, r) +    def mod_comb(self, n, k): +        if n == 0 and k == 0: +            return 1 +        elif n < k or k < 0: +            return 0 +        else: +            return ( +                self.fac[n] +                * pow(self.fac[n - k], self.mod - 2, self.mod) +                * pow(self.fac[k], self.mod - 2, self.mod) +                % self.mod +            ) + +    def mod_comb_with_rep(self, n, k): +        return self.mod_comb(n + k - 1, k) +    ans = 0 +    MOD = 10**9 + 7 +    modcomb = ModComb(S + 1, MOD) -    ans = 0 -        mod = S - i * 3 -        ans += combinations_with_replacement_count(mod + 1, i - 1) % (10**9 + 7) -    ans %= 10**9 + 7 +        res = S - i * 3 +        ans += modcomb.mod_comb_with_rep(res + 1, i - 1) +        ans %= MOD