Answer
Consider the symbolic form of the conditional statement as \[p\vee \left( \sim r\to s \right)\].
Here \[\sim r\] is antecedent.
Use De Morgan’s law to negate the conjunction negate each component and change \[\wedge \] to \[\vee \] and change \[\to \] to \[\wedge \].
The negation of \[p\vee \left( \sim r\to s \right)\] is \[\sim p\wedge \left( \sim r\wedge \sim s \right)\].