
# 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, stdout, setrecursionlimit

from collections import deque, defaultdict, Counter

from heapq import heappush, heappop

from functools import lru_cache

import math



setrecursionlimit(10**6)

rl = lambda: stdin.readline()

rll = lambda: stdin.readline().split()

rli = lambda: list(map(int, stdin.readline().split()))

rlf = lambda: list(map(float, stdin.readline().split()))



INF, NINF = float('inf'), float('-inf')

MOD = 10**9 + 7



def main():

	s = int(rl())



	@lru_cache(None)

	def dp(currsum):

		if currsum == s: return 1

		cnt = 0

		for d in range(3, 2001):

			if currsum + d <= s:

				cnt += dp(currsum + d)

				cnt %= MOD 

		return cnt

	print((dp(0)))

	stdout.close()



if __name__ == "__main__":

	main()

# optimized version of the same code:

from sys import stdin, stdout, setrecursionlimit

from collections import deque, defaultdict, Counter

from heapq import heappush, heappop

from functools import lru_cache

import math



#setrecursionlimit(10**6)

rl = lambda: stdin.readline()

rll = lambda: stdin.readline().split()

rli = lambda: list(map(int, stdin.readline().split()))

rlf = lambda: list(map(float, stdin.readline().split()))



INF, NINF = float('inf'), float('-inf')

MOD = 10**9 + 7



def main():

	s = int(rl())



	def binom_tables(n, q):

		fact = [1 for _ in range(n + 1)]

		inv = [1 for _ in range(n + 1)]

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

			fact[i] = (fact[i-1] * i) % q

			inv[i] = pow(fact[i], q-2, q)

		return fact, inv



	F, I = binom_tables(s + 700, MOD)



	def binom(n, k, q):

		return (F[n]*((I[k]*I[n-k])%q))%q



	ans = 0

	for r in range(1, 700):

		objects = s - 3*r

		if objects + r - 1 < objects or objects < 0: 

			break

		x = binom(objects + r - 1, objects, MOD)

		ans += x

		ans %= MOD 



	print(ans)

	stdout.close()



if __name__ == "__main__":

	main()
from sys import stdin, stdout, setrecursionlimit
from collections import deque, defaultdict, Counter
from heapq import heappush, heappop
from functools import lru_cache
import math

setrecursionlimit(10**6)
rl = lambda: stdin.readline()
rll = lambda: stdin.readline().split()
rli = lambda: list(map(int, stdin.readline().split()))
rlf = lambda: list(map(float, stdin.readline().split()))
INF, NINF = float("inf"), float("-inf")
MOD = 10**9 + 7


def main():
    s = int(rl())

    @lru_cache(None)
    def dp(currsum):
        if currsum == s:
            return 1
        cnt = 0
        for d in range(3, 2001):
            if currsum + d <= s:
                cnt += dp(currsum + d)
                cnt %= MOD
        return cnt

    print((dp(0)))
    stdout.close()


if __name__ == "__main__":
    main()

from sys import stdin, stdout, setrecursionlimit
from collections import deque, defaultdict, Counter
from heapq import heappush, heappop
from functools import lru_cache
import math

# setrecursionlimit(10**6)
rl = lambda: stdin.readline()
rll = lambda: stdin.readline().split()
rli = lambda: list(map(int, stdin.readline().split()))
rlf = lambda: list(map(float, stdin.readline().split()))
INF, NINF = float("inf"), float("-inf")
MOD = 10**9 + 7


def main():
    s = int(rl())

    def binom_tables(n, q):
        fact = [1 for _ in range(n + 1)]
        inv = [1 for _ in range(n + 1)]
        for i in range(1, n + 1):
            fact[i] = (fact[i - 1] * i) % q
            inv[i] = pow(fact[i], q - 2, q)
        return fact, inv

    F, I = binom_tables(s + 700, MOD)

    def binom(n, k, q):
        return (F[n] * ((I[k] * I[n - k]) % q)) % q

    ans = 0
    for r in range(1, 700):
        objects = s - 3 * r
        if objects + r - 1 < objects or objects < 0:
            break
        x = binom(objects + r - 1, objects, MOD)
        ans += x
        ans %= MOD
    print(ans)
    stdout.close()


if __name__ == "__main__":
    main()

-setrecursionlimit(10**6) +# setrecursionlimit(10**6) -    @lru_cache(None) -    def dp(currsum): -        if currsum == s: -            return 1 -        cnt = 0 -        for d in range(3, 2001): -            if currsum + d <= s: -                cnt += dp(currsum + d) -                cnt %= MOD -        return cnt +    def binom_tables(n, q): +        fact = [1 for _ in range(n + 1)] +        inv = [1 for _ in range(n + 1)] +        for i in range(1, n + 1): +            fact[i] = (fact[i - 1] * i) % q +            inv[i] = pow(fact[i], q - 2, q) +        return fact, inv -    print((dp(0))) +    F, I = binom_tables(s + 700, MOD) + +    def binom(n, k, q): +        return (F[n] * ((I[k] * I[n - k]) % q)) % q + +    ans = 0 +    for r in range(1, 700): +        objects = s - 3 * r +        if objects + r - 1 < objects or objects < 0: +            break +        x = binom(objects + r - 1, objects, MOD) +        ans += x +        ans %= MOD +    print(ans)