A9732. Queue
编程题
普及/提高-
知识点
题目描述
During the lunch break all $n$ Berland State University students lined up in the food court. However, it turned out that the food court, too, has a lunch break and it temporarily stopped working.
Standing in a queue that isn't being served is so boring! So, each of the students wrote down the number of the student ID of the student that stands in line directly in front of him, and the student that stands in line directly behind him. If no one stands before or after a student (that is, he is the first one or the last one), then he writes down number 0 instead (in Berland State University student IDs are numerated from $1$ ).
After that, all the students went about their business. When they returned, they found out that restoring the queue is not such an easy task.
Help the students to restore the state of the queue by the numbers of the student ID's of their neighbors in the queue.
Standing in a queue that isn't being served is so boring! So, each of the students wrote down the number of the student ID of the student that stands in line directly in front of him, and the student that stands in line directly behind him. If no one stands before or after a student (that is, he is the first one or the last one), then he writes down number 0 instead (in Berland State University student IDs are numerated from $1$ ).
After that, all the students went about their business. When they returned, they found out that restoring the queue is not such an easy task.
Help the students to restore the state of the queue by the numbers of the student ID's of their neighbors in the queue.
输入格式
During the lunch break all $n$ Berland State University students lined up in the food court. However, it turned out that the food court, too, has a lunch break and it temporarily stopped working.
Standing in a queue that isn't being served is so boring! So, each of the students wrote down the number of the student ID of the student that stands in line directly in front of him, and the student that stands in line directly behind him. If no one stands before or after a student (that is, he is the first one or the last one), then he writes down number 0 instead (in Berland State University student IDs are numerated from $1$ ).
After that, all the students went about their business. When they returned, they found out that restoring the queue is not such an easy task.
Help the students to restore the state of the queue by the numbers of the student ID's of their neighbors in the queue.
Standing in a queue that isn't being served is so boring! So, each of the students wrote down the number of the student ID of the student that stands in line directly in front of him, and the student that stands in line directly behind him. If no one stands before or after a student (that is, he is the first one or the last one), then he writes down number 0 instead (in Berland State University student IDs are numerated from $1$ ).
After that, all the students went about their business. When they returned, they found out that restoring the queue is not such an easy task.
Help the students to restore the state of the queue by the numbers of the student ID's of their neighbors in the queue.
输出格式
During the lunch break all $n$ Berland State University students lined up in the food court. However, it turned out that the food court, too, has a lunch break and it temporarily stopped working.
Standing in a queue that isn't being served is so boring! So, each of the students wrote down the number of the student ID of the student that stands in line directly in front of him, and the student that stands in line directly behind him. If no one stands before or after a student (that is, he is the first one or the last one), then he writes down number 0 instead (in Berland State University student IDs are numerated from $1$ ).
After that, all the students went about their business. When they returned, they found out that restoring the queue is not such an easy task.
Help the students to restore the state of the queue by the numbers of the student ID's of their neighbors in the queue.
Standing in a queue that isn't being served is so boring! So, each of the students wrote down the number of the student ID of the student that stands in line directly in front of him, and the student that stands in line directly behind him. If no one stands before or after a student (that is, he is the first one or the last one), then he writes down number 0 instead (in Berland State University student IDs are numerated from $1$ ).
After that, all the students went about their business. When they returned, they found out that restoring the queue is not such an easy task.
Help the students to restore the state of the queue by the numbers of the student ID's of their neighbors in the queue.
输入输出样例
输入 #1
4 92 31 0 7 31 0 7 141
输出 #1
92 7 31 141
说明/提示
The picture illustrates the queue for the first sample.
