题目描述
Problem Statement
Among the sequences P that are permutations of $(1, 2, \dots, N)$ and satisfy the condition below, find the lexicographically smallest sequence.
- For each $i = 1, \dots, M, A_i$ appears earlier than B_i in P.
If there is no such P, print -1.
Input
Input is given from Standard Input in the following format:
N M
A_1 B_1
$\vdots$
A_M B_M
Output
Print the answer.
Constraints
- $2 \leq N \leq 2 \times 10^5$
- $1 \leq M \leq 2 \times 10^5$
- $1 \leq A_i, B_i \leq N$
- $A_i \neq B_i$
- All values in input are integers.
Sample Input 1
4 3
2 1
3 4
2 4
Sample Output 1
2 1 3 4
The following five permutations P satisfy the condition: (2, 1, 3, 4), (2, 3, 1, 4), (2, 3, 4, 1), (3, 2, 1, 4), (3, 2, 4, 1). The lexicographically smallest among them is (2, 1, 3, 4).
Sample Input 2
2 3
1 2
1 2
2 1
Sample Output 2
-1
No permutations P satisfy the condition.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
4 3
2 1
3 4
2 4
样例输出
2 1 3 4