
# 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:

#!/usr/bin/env python3

def main():

    import numpy as np



    N = int(eval(input()))

    happiness = [list(map(int, input().split())) for _ in range(N)]



    dp = np.zeros((N, 3), dtype=np.int64)

    dp[0] = happiness[0]

    for i in range(1, N):

        for a, yesterday in enumerate(dp[i - 1]):

            for b, today in enumerate(happiness[i]):

                if a == b:

                    continue

                dp[i][b] = max(dp[i][b], yesterday + today)

    print((max(dp[-1])))





if __name__ == '__main__':

    main()


# optimized version of the same code:

#!/usr/bin/env python3

def main():

    N = int(eval(input()))

    happiness = [list(map(int, input().split())) for _ in range(N)]



    dp = [0, 0, 0]

    for a, b, c in happiness:

        dp = [max(dp[1], dp[2]) + a,

              max(dp[0], dp[2]) + b,

              max(dp[0], dp[1]) + c]

    print((max(dp)))





if __name__ == '__main__':

    main()

#!/usr/bin/env python3
def main():
    import numpy as np

    N = int(eval(input()))
    happiness = [list(map(int, input().split())) for _ in range(N)]
    dp = np.zeros((N, 3), dtype=np.int64)
    dp[0] = happiness[0]
    for i in range(1, N):
        for a, yesterday in enumerate(dp[i - 1]):
            for b, today in enumerate(happiness[i]):
                if a == b:
                    continue
                dp[i][b] = max(dp[i][b], yesterday + today)
    print((max(dp[-1])))


if __name__ == "__main__":
    main()

#!/usr/bin/env python3
def main():
    N = int(eval(input()))
    happiness = [list(map(int, input().split())) for _ in range(N)]
    dp = [0, 0, 0]
    for a, b, c in happiness:
        dp = [max(dp[1], dp[2]) + a, max(dp[0], dp[2]) + b, max(dp[0], dp[1]) + c]
    print((max(dp)))


if __name__ == "__main__":
    main()

-    import numpy as np - -    dp = np.zeros((N, 3), dtype=np.int64) -    dp[0] = happiness[0] -    for i in range(1, N): -        for a, yesterday in enumerate(dp[i - 1]): -            for b, today in enumerate(happiness[i]): -                if a == b: -                    continue -                dp[i][b] = max(dp[i][b], yesterday + today) -    print((max(dp[-1]))) +    dp = [0, 0, 0] +    for a, b, c in happiness: +        dp = [max(dp[1], dp[2]) + a, max(dp[0], dp[2]) + b, max(dp[0], dp[1]) + c] +    print((max(dp)))