A stack of two queues
Two stacks a queue
push the stack
pop stack
pop stack of non-null, push impenetrability pop stack
pop the stack is empty, push poured pop up push is empty.
A stack of two queues
Two stacks a queue
push the stack
pop stack
pop stack of non-null, push impenetrability pop stack
pop the stack is empty, push poured pop up push is empty.