위상 정렬!

	import sys
	from collections import deque
	n, m = map(int, sys.stdin.readline().split())
	ind = [0]*(n+1)
	graph = [[0] for _ in range(n+1)]
	for i in range(m):
	a, b = map(int, sys.stdin.readline().split())
	graph[a].append(b)
	ind[b] += 1
	queue = deque()
	for i in range(1, n+1):
	if ind[i] == 0:
	queue.append(i)
	while queue:
	now = queue.popleft()
	print(now, end=' ')
	for i in graph[now]:
	ind[i] -= 1
	if ind[i] == 0:
	queue.append(i)

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