In this task, you are given two phrases: Head and Tail, separated with <sep>. The Head and the Tail events are short phrases possibly involving participants. The names of specific people have been replaced by generic words (e.g., PersonX, PersonY, PersonZ). PersonX is always the subject of the event. You have to determine whether PersonX needs what is mentioned in the Tail before the Head or not. Here need is a precondition for PersonX to achieve the event. For example, in order for PersonX to give PersonY gifts, PersonX must first buy the presents. Classify your answers into "Yes" and "No". The phrase may also contain "___", a placeholder that can be an object, a person, and/or an action.

[EX Q]: Head: PersonX keeps PersonY calm<sep>Tail: to find personY
[EX A]: Yes

[EX Q]: Head: PersonX catches the thief<sep>Tail: chasing a thief
[EX A]: Yes

[EX Q]: Head: PersonX keeps track of PersonY<sep>Tail: to be PersonY's stalker
[EX A]:
Yes