
# 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:

import sys, os, math, bisect, itertools, collections, heapq, queue, copy, array



# from scipy.sparse.csgraph import csgraph_from_dense, floyd_warshall

# from decimal import Decimal

# from collections import defaultdict, deque



sys.setrecursionlimit(10000000)



ii = lambda: int(sys.stdin.buffer.readline().rstrip())

il = lambda: list(map(int, sys.stdin.buffer.readline().split()))

fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))

iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]



iss = lambda: sys.stdin.buffer.readline().decode().rstrip()

sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))

isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]



lcm = lambda x, y: (x * y) // math.gcd(x, y)



MOD = 10 ** 9 + 7

INF = float('inf')





def main():

    if os.getenv("LOCAL"):

        sys.stdin = open("input.txt", "r")



    S = ii()

    dp = [0] * (S + 1)



    dp[0] = 1

    # 0 <= i <= Sの範囲を探索

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

        # 0 <= j <= i - 3の範囲で、

        # 間仕切りを置くことができる個数の合計を集計

        for j in range(0, i - 3 + 1):

            dp[i] += dp[j]

            dp[i] %= MOD

    print((dp[-1]))





if __name__ == '__main__':

    main()


# optimized version of the same code:

import sys, os, math, bisect, itertools, collections, heapq, queue, copy, array



# from scipy.sparse.csgraph import csgraph_from_dense, floyd_warshall

# from decimal import Decimal

# from collections import defaultdict, deque



sys.setrecursionlimit(10000000)



ii = lambda: int(sys.stdin.buffer.readline().rstrip())

il = lambda: list(map(int, sys.stdin.buffer.readline().split()))

fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))

iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]



iss = lambda: sys.stdin.buffer.readline().decode().rstrip()

sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))

isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]



lcm = lambda x, y: (x * y) // math.gcd(x, y)



MOD = 10 ** 9 + 7

INF = float('inf')





def main():

    if os.getenv("LOCAL"):

        sys.stdin = open("input.txt", "r")



    S = ii()

    dp = [0] * (S + 1)



    dp[0] = 1

    # 0 <= i <= Sの範囲を探索

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

        # 0 <= j <= i - 3の範囲で、

        # 間仕切りを置くことができる個数の合計を集計

        if i > 2:

            dp[i] = sum(dp[0:i - 2])

            dp[i] %= MOD

    print((dp[-1]))





if __name__ == '__main__':

    main()

import sys, os, math, bisect, itertools, collections, heapq, queue, copy, array

# from scipy.sparse.csgraph import csgraph_from_dense, floyd_warshall
# from decimal import Decimal
# from collections import defaultdict, deque
sys.setrecursionlimit(10000000)
ii = lambda: int(sys.stdin.buffer.readline().rstrip())
il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]
iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]
lcm = lambda x, y: (x * y) // math.gcd(x, y)
MOD = 10**9 + 7
INF = float("inf")


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")
    S = ii()
    dp = [0] * (S + 1)
    dp[0] = 1
    # 0 <= i <= Sの範囲を探索
    for i in range(1, S + 1):
        # 0 <= j <= i - 3の範囲で、
        # 間仕切りを置くことができる個数の合計を集計
        for j in range(0, i - 3 + 1):
            dp[i] += dp[j]
            dp[i] %= MOD
    print((dp[-1]))


if __name__ == "__main__":
    main()

import sys, os, math, bisect, itertools, collections, heapq, queue, copy, array

# from scipy.sparse.csgraph import csgraph_from_dense, floyd_warshall
# from decimal import Decimal
# from collections import defaultdict, deque
sys.setrecursionlimit(10000000)
ii = lambda: int(sys.stdin.buffer.readline().rstrip())
il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]
iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]
lcm = lambda x, y: (x * y) // math.gcd(x, y)
MOD = 10**9 + 7
INF = float("inf")


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")
    S = ii()
    dp = [0] * (S + 1)
    dp[0] = 1
    # 0 <= i <= Sの範囲を探索
    for i in range(1, S + 1):
        # 0 <= j <= i - 3の範囲で、
        # 間仕切りを置くことができる個数の合計を集計
        if i > 2:
            dp[i] = sum(dp[0 : i - 2])
            dp[i] %= MOD
    print((dp[-1]))


if __name__ == "__main__":
    main()

-        for j in range(0, i - 3 + 1): -            dp[i] += dp[j] +        if i > 2: +            dp[i] = sum(dp[0 : i - 2])