
# 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:

# coding: utf-8





def solve(*args: str) -> str:

    k = int(args[0])



    l = 9*(k//7 if k % 7 == 0 else k)

    if l % 2 == 0 or l % 5 == 0:

        return '-1'



    r = phi = l

    for i in range(2, int(-pow(l, 1/2))):

        if r % i == 0:

            phi = phi//i*(i-1)

            while r % i:

                r //= i



    a = 10 % l

    ret = 1

    while(a != 1):

        a = a*10 % l

        ret += 1

        if phi < ret:

            ret = -1

            break



    return str(ret)





if __name__ == "__main__":

    print((solve(*(open(0).read().splitlines()))))


# optimized version of the same code:

# coding: utf-8

from math import sqrt





def solve(*args: str) -> str:

    k = int(args[0])



    l = 9*(k//7 if 0 == k % 7 else k)

    if 0 == l % 2 or 0 == l % 5:

        return '-1'



    r = phi = l

    for i in range(2, int(sqrt(l)+1)):

        if 0 == r % i:

            phi = phi*(i-1)//i

            while 0 == r % i:

                r //= i

    if 1 < r:

        phi = phi*(r-1)//r



    D = set()

    for d in range(1, int(sqrt(phi)+1)):

        if 0 == phi % d:

            D.add(d)

            D.add(phi//d)



    ret = -1

    for m in sorted(D):

        if 1 == pow(10, m, l):

            ret = m

            break



    return str(ret)





if __name__ == "__main__":

    print((solve(*(open(0).read().splitlines()))))

# coding: utf-8
def solve(*args: str) -> str:
    k = int(args[0])
    l = 9 * (k // 7 if k % 7 == 0 else k)
    if l % 2 == 0 or l % 5 == 0:
        return "-1"
    r = phi = l
    for i in range(2, int(-pow(l, 1 / 2))):
        if r % i == 0:
            phi = phi // i * (i - 1)
            while r % i:
                r //= i
    a = 10 % l
    ret = 1
    while a != 1:
        a = a * 10 % l
        ret += 1
        if phi < ret:
            ret = -1
            break
    return str(ret)


if __name__ == "__main__":
    print((solve(*(open(0).read().splitlines()))))

# coding: utf-8
from math import sqrt


def solve(*args: str) -> str:
    k = int(args[0])
    l = 9 * (k // 7 if 0 == k % 7 else k)
    if 0 == l % 2 or 0 == l % 5:
        return "-1"
    r = phi = l
    for i in range(2, int(sqrt(l) + 1)):
        if 0 == r % i:
            phi = phi * (i - 1) // i
            while 0 == r % i:
                r //= i
    if 1 < r:
        phi = phi * (r - 1) // r
    D = set()
    for d in range(1, int(sqrt(phi) + 1)):
        if 0 == phi % d:
            D.add(d)
            D.add(phi // d)
    ret = -1
    for m in sorted(D):
        if 1 == pow(10, m, l):
            ret = m
            break
    return str(ret)


if __name__ == "__main__":
    print((solve(*(open(0).read().splitlines()))))

+from math import sqrt + + -    l = 9 * (k // 7 if k % 7 == 0 else k) -    if l % 2 == 0 or l % 5 == 0: +    l = 9 * (k // 7 if 0 == k % 7 else k) +    if 0 == l % 2 or 0 == l % 5: -    for i in range(2, int(-pow(l, 1 / 2))): -        if r % i == 0: -            phi = phi // i * (i - 1) -            while r % i: +    for i in range(2, int(sqrt(l) + 1)): +        if 0 == r % i: +            phi = phi * (i - 1) // i +            while 0 == r % i: -    a = 10 % l -    ret = 1 -    while a != 1: -        a = a * 10 % l -        ret += 1 -        if phi < ret: -            ret = -1 +    if 1 < r: +        phi = phi * (r - 1) // r +    D = set() +    for d in range(1, int(sqrt(phi) + 1)): +        if 0 == phi % d: +            D.add(d) +            D.add(phi // d) +    ret = -1 +    for m in sorted(D): +        if 1 == pow(10, m, l): +            ret = m