class Queue:

def __init__(self):

self.pushstack = []

self.popstack = []

def push(self, x: int) -> None:

self.pushstack.append(x)

def pop(self) -> int:

self.peek()

return self.popstack.pop()

def peek(self) -> int:

if not self.popstack:

while self.pushstack:

self.popstack.append(self.pushstack.pop())

return self.popstack[-1]

def empty(self) -> bool:

return not self.pushstack and not self.popstack

class QueuePush:

def __init__(self):

self.stack = []

self.stack_two = []

def push(self, x: int) -> None:

while self.stack:

top = self.stack.pop()

self.stack_two.append(top)

self.stack.append(x)

while self.stack_two:

top = self.stack_two.pop()

self.stack.append(top)

def pop(self) -> int:

return self.stack.pop()

def peek(self) -> int:

return self.stack[-1]

def empty(self) -> bool:

return not self.stack