import time, sys

def watch(start):

    laps = [start]
    while True:

        option = raw_input("> ")
        if option == "stop":
            end = time.time()
            break

        elif option == "lap": laps.append(time.time())

    print end - start

    for i in range(1, len(laps)):
        print ("Lap %d: %f" % ( i, laps[i] - laps[i - 1]))


def wrapper():

    option = raw_input("Watch state: ")
    if option == "start": watch(time.time())
    elif option in ("quit", "exit"): sys.exit()
    wrapper()

wrapper()