$1.$Write the subroutine code to insert an element onto a queue?$2.$Write the subroutine code to delete an element from a queue?$3.$Suppose an initially empty stack S$1$ has performed a total of $33$ push operations, $13$ top operations, and $20$ pop operations, $5$ of which returned null to indicate an empty stack. What is the current size of S$1?4.$Implement the Queue ADT using the Java ArrayList class $($without using the built$-$in Java Queue class$).$ You should implement the five functions: dequeue, front, enqueue, size, and isEmpty.