from structures import run_operations

class TwoStackQueue:
    def __init__(self):
        self.incoming, self.outgoing = [], []

    def push(self, value):
        self.incoming.append(value)

    def _prepare(self):
        if not self.outgoing:
            while self.incoming:
                self.outgoing.append(self.incoming.pop())

    def pop(self):
        self._prepare()
        return self.outgoing.pop()

    def peek(self):
        self._prepare()
        return self.outgoing[-1]

    def empty(self):
        return not self.incoming and not self.outgoing