class JobQ(list):
    add = list.append
    
    def next(self):
        return self.pop(0)
    
    def check(self):
        if not self:
            return None
        return self.data[0]
    
    def __str__(self):
        res = " "
        for job in self:
            (filename,length) = job
            res += " %s(%d)" % (filename, length)
        return res