Alice: first toss: head. Second toss: head. She can take that second toss as the begining of the new sequence and if she gets tail on the third toss she is done

Alice: first toss: head. Second toss: head. She can take that second toss as the begining of the new sequence and if she gets tail on the third toss she is done. In Bob's case, if he gets tail on the second toss, that toss no longer counts and he must get head for the new streak to begin.