Broken Keyboard

Description

You're typing a long text with a broken keyboard. Well it's not so badly broken. The only problem with the keyboard is that sometimes the "home" key or the "end" key gets automatically pressed (internally).

You're not aware of this issue, since you're focusing on the text and did not even turn on the monitor! After you finished typing, you can see a text on the screen (if you turn on the monitor).

In Chinese, we can call it Beiju. Your task is to find the Beiju text.

Input

There are several test cases. Each test case is a single line containing at least one and at most 100,000 letters, underscores and two special characters '[' and ']'. '[' means the "Home" key is pressed internally, and ']' means the "End" key is pressed internally. The input is terminated by end-of-file (EOF). The size of input file does not exceed 5MB.

Output

For each case, print the Beiju text on the screen.

Sample Input

This_is_a_[Beiju]_text[[]][][]Happy_Birthday_to_Tsinghua_University

Output for the Sample Input

BeijuThis_is_a__textHappy_Birthday_to_Tsinghua_University

对链表的应用。本题因为涉及到在数组中插入，用单纯的数组显然不可能，而之前学的STL也仅仅是在头部和尾部进行操作，所以我们使用链表。传统意义上的链表多用指针来表示，但是在算法竞赛中，使用指针实在不是上上之选，而且也过于麻烦，为了方便起见，常常在链表的第一个元素之前放一个虚拟结点。last永远指向数组的最后一个字符，cur指向插入的前一个位置。代码如下：

#include<cstdio>#include<cstring>using namespace std;const int maxn=100000+5;char s[maxn];int next[maxn];int main(){while(scanf("%s",s+1)==1)   //从s【1】开始存储{int len=strlen(s+1);int cur=0,last=0;next[0]=0;for(int i=1;i<=len;i++){if(s[i]=='[') cur=0;else if(s[i]==']') cur=last;else{next[i]=next[cur];next[cur]=i;if(cur==last) last=i;cur=i;}}for(int i=next[0];i!=0;i=next[i])printf("%c",s[i]);printf("\n");}return 0;}