
# 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 functools import lru_cache

import sys



sys.setrecursionlimit(2000)



s = int(eval(input()))

mod = 10 ** 9 + 7





@lru_cache(maxsize=None)

def dfs(n):

    if n <= 2:

        return 0

    elif 3<=n<=5:

        return 1

    else:

        count = 1

        for i in range(3, n + 1):

            count += dfs(n - i)

            count %= mod



        return count % mod





ans = dfs(s)

print(ans)


# optimized version of the same code:

s = int(eval(input()))

mod = 10 ** 9 + 7



dp = [0] * (s + 1)

dp[0] = 1



x = 0

for i in range(3, s + 1):

    x += dp[i - 3]

    dp[i] = x % mod



ans = dp[s] % mod

print(ans)

from functools import lru_cache
import sys

sys.setrecursionlimit(2000)
s = int(eval(input()))
mod = 10**9 + 7


@lru_cache(maxsize=None)
def dfs(n):
    if n <= 2:
        return 0
    elif 3 <= n <= 5:
        return 1
    else:
        count = 1
        for i in range(3, n + 1):
            count += dfs(n - i)
            count %= mod
        return count % mod


ans = dfs(s)
print(ans)

s = int(eval(input()))
mod = 10**9 + 7
dp = [0] * (s + 1)
dp[0] = 1
x = 0
for i in range(3, s + 1):
    x += dp[i - 3]
    dp[i] = x % mod
ans = dp[s] % mod
print(ans)

-from functools import lru_cache -import sys - -sys.setrecursionlimit(2000) - - -@lru_cache(maxsize=None) -def dfs(n): -    if n <= 2: -        return 0 -    elif 3 <= n <= 5: -        return 1 -    else: -        count = 1 -        for i in range(3, n + 1): -            count += dfs(n - i) -            count %= mod -        return count % mod - - -ans = dfs(s) +dp = [0] * (s + 1) +dp[0] = 1 +x = 0 +for i in range(3, s + 1): +    x += dp[i - 3] +    dp[i] = x % mod +ans = dp[s] % mod