That sounds a bit like the SQuAD 2.0 challenge, but simpler.
In SQuAD 2.0 a model is given a question, and a passage of information. It has to select the start and end points of where the answer is contained in the passage.
Your problem is simpler in that there is no question - you just have to have a model that can identify the start and end positions that _you_ will select.