- Time limit: 1.00 s
- Memory limit: 512 MB
You want to complete n courses that have requirements of the form "course a has to be completed before course b".
You want to complete course 1 as soon as possible. If there are several ways to do this, you want then to complete course 2 as soon as possible, and so on.
Your task is to determine the order in which you complete the courses.
The first input line has two integers n and m: the number of courses and requirements. The courses are numbered 1,2,\dots,n.
Then, there are m lines describing the requirements. Each line has two integers a and b: course a has to be completed before course b.
You can assume that there is at least one valid schedule.
Print one line having n integers: the order in which you complete the courses.
- 1 \le n \le 10^5
- 1 \le m \le 2 \cdot 10^5
- 1 \le a,b \le n
4 2 2 1 2 3
2 1 3 4