
# 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, re

from collections import deque, defaultdict, Counter

from math import ceil, sqrt, hypot, factorial, pi, sin, cos, radians, gcd

from itertools import accumulate, permutations, combinations, product, groupby, combinations_with_replacement

from operator import itemgetter, mul

from copy import deepcopy

from string import ascii_lowercase, ascii_uppercase, digits

from bisect import bisect, bisect_left

from heapq import heappush, heappop

from functools import reduce, lru_cache

def input(): return sys.stdin.readline().strip()

def INT(): return int(eval(input()))

def MAP(): return list(map(int, input().split()))

def LIST(): return list(map(int, input().split()))

def ZIP(n): return list(zip(*(MAP() for _ in range(n))))

sys.setrecursionlimit(10 ** 9)

INF = float('inf')

mod = 10 ** 9 + 7



S = INT()



@lru_cache(maxsize=None)

def rec(x):

    if x == 0: return 1



    ret = 0

    for i in range(x-2):

        ret += rec(i)

        ret %= mod

    return ret



print((rec(S)))


# optimized version of the same code:

import sys, re

from collections import deque, defaultdict, Counter

from math import ceil, sqrt, hypot, factorial, pi, sin, cos, radians, gcd

from itertools import accumulate, permutations, combinations, product, groupby, combinations_with_replacement

from operator import itemgetter, mul

from copy import deepcopy

from string import ascii_lowercase, ascii_uppercase, digits

from bisect import bisect, bisect_left

from heapq import heappush, heappop

from functools import reduce, lru_cache

def input(): return sys.stdin.readline().strip()

def INT(): return int(eval(input()))

def MAP(): return list(map(int, input().split()))

def LIST(): return list(map(int, input().split()))

def ZIP(n): return list(zip(*(MAP() for _ in range(n))))

sys.setrecursionlimit(10 ** 9)

INF = float('inf')

mod = 10 ** 9 + 7



S = INT()



@lru_cache(maxsize=None)

def rec(x):

    if x == 0: return 1



    ret = 0

    if x >= 3:

        return (rec(x-1)+rec(x-3))%mod

    else:

        return 0



print((rec(S)))

import sys, re
from collections import deque, defaultdict, Counter
from math import ceil, sqrt, hypot, factorial, pi, sin, cos, radians, gcd
from itertools import (
    accumulate,
    permutations,
    combinations,
    product,
    groupby,
    combinations_with_replacement,
)
from operator import itemgetter, mul
from copy import deepcopy
from string import ascii_lowercase, ascii_uppercase, digits
from bisect import bisect, bisect_left
from heapq import heappush, heappop
from functools import reduce, lru_cache


def input():
    return sys.stdin.readline().strip()


def INT():
    return int(eval(input()))


def MAP():
    return list(map(int, input().split()))


def LIST():
    return list(map(int, input().split()))


def ZIP(n):
    return list(zip(*(MAP() for _ in range(n))))


sys.setrecursionlimit(10**9)
INF = float("inf")
mod = 10**9 + 7
S = INT()


@lru_cache(maxsize=None)
def rec(x):
    if x == 0:
        return 1
    ret = 0
    for i in range(x - 2):
        ret += rec(i)
        ret %= mod
    return ret


print((rec(S)))

import sys, re
from collections import deque, defaultdict, Counter
from math import ceil, sqrt, hypot, factorial, pi, sin, cos, radians, gcd
from itertools import (
    accumulate,
    permutations,
    combinations,
    product,
    groupby,
    combinations_with_replacement,
)
from operator import itemgetter, mul
from copy import deepcopy
from string import ascii_lowercase, ascii_uppercase, digits
from bisect import bisect, bisect_left
from heapq import heappush, heappop
from functools import reduce, lru_cache


def input():
    return sys.stdin.readline().strip()


def INT():
    return int(eval(input()))


def MAP():
    return list(map(int, input().split()))


def LIST():
    return list(map(int, input().split()))


def ZIP(n):
    return list(zip(*(MAP() for _ in range(n))))


sys.setrecursionlimit(10**9)
INF = float("inf")
mod = 10**9 + 7
S = INT()


@lru_cache(maxsize=None)
def rec(x):
    if x == 0:
        return 1
    ret = 0
    if x >= 3:
        return (rec(x - 1) + rec(x - 3)) % mod
    else:
        return 0


print((rec(S)))

-    for i in range(x - 2): -        ret += rec(i) -        ret %= mod -    return ret +    if x >= 3: +        return (rec(x - 1) + rec(x - 3)) % mod +    else: +        return 0