def main():
    # compute the sum of the numbers
    # entered by the user. The user stops
    # by hitting the enter key.

    sum = 0

    # read first value
    strInput = raw_input("enter 1st number (enter to quit):")

    while strInput != "":
        number = float(strInput)
        sum += number

        # read next value
        strInput = raw_input("enter next number (enter to quit): ")

    print "sum=", sum

main()