def __init__(self):
        self.queue = []
        self.stack = []

    def pushCharacter(self, char):
        self.stack.append(char)
    def enqueueCharacter(self, char):
        self.queue.append(char)
    def popCharacter(self):
        return self.stack.pop(-1)
    def dequeueCharacter(self):
        return self.queue.pop(0)