Concur with that. I also reccommend a spare flashlight.

A couple of years back in a high sierra backpack, the guide took most of the group on what was supposed to be a 3 hour dayhike. I stayed in camp with mild altitude sickness. 9 hours later they got back into camp (never go off trail with a 1:200,000 scale topo as your only reference) minus one hiker. I went after him, but my flashlight died 50 yards into the trees, and my spares were back at camp. The lost hiker wandered in the next morning after losing the trail when it crossed a stream.