"""
Converts a binary number to a decimal number.
"""


def bin_to_dec(number):
    """Algorithm that converts a binary number to a decimal number.

    Receives and returns a string."""

    # get the index of power of first digit
    # e.g. 1001 → first index power is 3 (2^3)
    first_power = len(number) - 1

    total = 0  # initialize variable to store final result

    # iterate over each number and if it is '1', calculate the value
    # based on its position and add it to the total
    for index, char in enumerate(number):
        if char == '1':
            total += 2 ** (first_power - index)

    # give back the answer to the script
    return total


if __name__ == '__main__':
    # retrieve binary number from input as string to parse
    BIN_NUM = input()

    # pass binary number to algorithm and store the result
    RESULT = bin_to_dec(BIN_NUM)

    # print the solution to the console
    print(RESULT)

"""
Converts a decimal number to a binary number.
"""


def dec_to_bin(number):
    """Algorithm that converts a decimal number to a binary number.

    Receives an integer and returns a string."""

    if number == 0:  # if number is 'zero', the answer is 'zero'
        return 0

    remainders = []  # list that stores the remainders

    # iterate over the initial given decimal and divide it by two
    # until it gets to 'zero'. At each step, add the remainder in
    # the above list
    while number > 0:
        remainders.append(number % 2)
        number = number // 2

    # reverse the list of remainders, as the first remainder is the
    # right most digit in the answer
    remainders.reverse()

    # concatenate all the digits from the list of remainders from left
    # to right to display the final binary number
    answer = ''
    for digit in remainders:
        answer += str(digit)

    # give the answer back to the script
    return answer


if __name__ == '__main__':
    # retrieve decimal number from input as integer
    DEC_NUM = int(input())

    # pass decimal number to algorithm and store the result
    RESULT = dec_to_bin(DEC_NUM)

    # print the solution to the console
    print(RESULT)