We may not be able to tell you how ABC's "Lost" will end.

But we can at least tell you when.

The saga of Oceanic Air Flight 815 will run for 48 more episodes after this season's May 23 finale, ABC announced yesterday.

They'll play out over three seasons, airing 16 uninterrupted episodes each year and concluding in the 2009-10 season.

In January, executive producers Damon Lindelof and Carlton Cuse had told reporters they planned to negotiate a firm exit date for the series in an apparent attempt to reassure viewers that they really do know how it's supposed to end.

Lindelof and Cuse will remain with the series throughout its run, according to ABC entertainment president Stephen McPherson, who, in a prepared statement, called the pair's continued participation "critical."

"We always envisioned 'Lost' as a show with a beginning, middle and end," said Lindelof and Cuse in a statement released by ABC. "By officially announcing exactly when that ending will be, the audience will now have the security of knowing that the story will play out as we've intended."

And though there are bound to be complaints about the scheduling plans - only 16 per season? - ABC's statement would seem to rule out a repeat of the lengthy (and unpopular) interruption between the first and second part of the current season, as well as the weeks of reruns that plagued Season 1.

ABC's statement didn't include a return date for the show, but USA Today reports that the three remaining seasons will air from February to May.

In other scheduling news, NBC yesterday jumped the gun by an entire week to give an early pickup to its psychic drama "Medium." Look for the rest of its 2007-08 schedule to be announced on May 14. *