1、初始化栈；2、判断栈是否为空；3、依次进站元素；4、输出栈的长度；5、输出栈的元素；6、输出栈序列-1, initialize the stack　2, determine the stack is empty　3, followed by stop elements　4, the length of the output stack　5, the output stack elements　6, the output stack sequence