in th in. and if for some reason that was to collapse, that would be a tragedy. if with we can b we build the h wi can build a dam to block the water from this cave. and we should be flying the best mechanisms to that site, let's empty it out, dam it up you, not in that order, and let's let them walk out the same way they walked in. i think that makes the most sense given the variables for their survival. >> so since the time line is tbd, lastly, just air quality, you are concerned about that. tell me why? >> i was concerned until they found this group. because something -- they have water. you need water to survive. he even a group of kids, but the average human can go two to three weeks without food. they had shelter. it was a relatively mild