from collections import defaultdict

class Graph:
	def __init__(self,vertices):
		self.graph = defaultdict(list)
		self.V = vertices

	def addEdge(self,u,v):
		self.graph[u].append(v)

	def topologicalSort(self):

		in_degree = [0]*(self.V)

		for i in self.graph:
			for j in self.graph[i]:
				in_degree[j] += 1

		queue = []
		for i in range(self.V):
			if in_degree[i] == 0:
				queue.append(i)

		cnt = 0

		top_order = []

		while queue:

			u = queue.pop(0)
			top_order.append(u)

			for i in self.graph[u]:
				in_degree[i] -= 1

				if in_degree[i] == 0:
					queue.append(i)

			cnt += 1

		if cnt != self.V:
			print ("Impossible")
		else :
			print (top_order)

n,m = input().split(" ")
n = int(n)
m = int(m)
g = Graph(n)

for i in range (m):
    u,v = input().split(" ")
    u = int(u)
    v = int(v)
    g.addEdge(u, v);
    m -= 1

g.topologicalSort()