Dimitry DungeonMap 3870			Сагура Николай, 392, сев. филиал DungeonMap 3975
t	1	from collections import defaultdict, deque	t	1	from collections import defaultdict, deque
	2	graph = defaultdict(list)		2	graph = defaultdict(list)
	3	while True:		3	while True:
	4	line = input().strip()		4	line = input().strip()
	5	if not line:		5	if not line:
	6	continue		6	continue
	7	if ' ' not in line:		7	if ' ' not in line:
	8	start = line		8	start = line
	9	end = input().strip()		9	end = input().strip()
	10	break		10	break
	11	a, b = line.split()		11	a, b = line.split()
	12	graph[a].append(b)		12	graph[a].append(b)
	13	graph[b].append(a)		13	graph[b].append(a)
	14	visited = set()		14	visited = set()
	15	queue = deque([start])		15	queue = deque([start])
	16	visited.add(start)		16	visited.add(start)
	17	while queue:		17	while queue:
	18	current = queue.popleft()		18	current = queue.popleft()
	19	if current == end:		19	if current == end:
	20	print('YES')		20	print('YES')
	21	exit()		21	exit()
	22	for neighbor in graph[current]:		22	for neighbor in graph[current]:
	23	if neighbor not in visited:		23	if neighbor not in visited:
	24	visited.add(neighbor)		24	visited.add(neighbor)
	25	queue.append(neighbor)		25	queue.append(neighbor)
	26	print('NO')		26	print('NO')

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