countdown timer

I need a countdown timer to place on my webpage. This timer will be used as an exercise timer. It should allow for the user to select the number of rounds to exercise. Then the user selects the time i.e. 45 seconds to exercise and a separate rest period i.e. 1:30 (one minute thitry seconds). There should be some audible signal at the end of the exercise portion and another at the end of the rest segement to signal the start of the next exercise round. The timer should run through the whole cycle until the end of all rounds. For example, the user selects 4 rounds the select each time segment. Round 1: Exercise 30 sec.(sound) Rest 60 sec. (sound) Round 2: Exercise 35 sec.(sound) Rest 50 sec. (sound) Round 3: Exercise 20 sec.(sound) Rest 35 sec. (sound) Round 4: Exercise 15 sec (sound) End. This should have the ability to select at least 6 exercise rounds.