
# 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:

def main():

    s = int(eval(input()))

    mod = 10**9 + 7



    dp = [0] * (s+1)

    dp[0] = 1

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

        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:

def main():

    s = int(eval(input()))

    mod = 10**9 + 7



    dp = [0] * (s+1)

    dp[0] = 1

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

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

#            dp[i] += dp[j]

#            dp[i] %= mod

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

        if i < 3:

            dp[i] = 0

        else:

            dp[i] = dp[i-1] + dp[i-3]

            dp[i] %= mod



    print((dp[-1]))





if __name__ == "__main__":

    main()

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


if __name__ == "__main__":
    main()

def main():
    s = int(eval(input()))
    mod = 10**9 + 7
    dp = [0] * (s + 1)
    dp[0] = 1
    #    for i in range(1, s+1):
    #        for j in range(0, (i-3)+1):
    #            dp[i] += dp[j]
    #            dp[i] %= mod
    for i in range(1, s + 1):
        if i < 3:
            dp[i] = 0
        else:
            dp[i] = dp[i - 1] + dp[i - 3]
            dp[i] %= mod
    print((dp[-1]))


if __name__ == "__main__":
    main()

+    #    for i in range(1, s+1): +    #        for j in range(0, (i-3)+1): +    #            dp[i] += dp[j] +    #            dp[i] %= mod -        for j in range(0, (i - 3) + 1): -            dp[i] += dp[j] +        if i < 3: +            dp[i] = 0 +        else: +            dp[i] = dp[i - 1] + dp[i - 3]