What are the soldiers in Act I of Hamlet Are Looking for?

Act 1 establishes these plot points: The new king, Hamlet's uncle, murdered Hamlet's father. His father's ghost appears to him to describe the murder and charge Hamlet with seeking revenge. Hamlet's mother committed adultery with Claudius before her husband's death and married Claudius with "unseemly" haste.

On a dark winter night outside Elsinore Castle in Denmark, an officer named Bernardo comes to relieve the watchman Francisco. In the heavy darkness, the men cannot see each other. Bernardo hears a footstep near him and cries, “Who’s there?” After both men ensure that the other is also a watchman, they relax. Cold, tired, and apprehensive from his many hours of guarding the castle, Francisco thanks Bernardo and prepares to go home and go to bed.

this is b. how railways dealt with people riding the trains without paying