import pprint
import itertools
import fileinput

nodes = []
edges = []
for raw in fileinput.input():
	line = raw.strip()
	if line == '': continue
	[a,b] = line.split('-')
	nodes += [a, b]
	edges.append((a, b))

nodes = list(set(nodes))
nodes.sort()

graph = [[0 for j in range(len(nodes))] for i in range(len(nodes))]

#pprint.pprint(graph)

for (a,b) in edges:
	i, j = nodes.index(a), nodes.index(b)
	graph[i][j] = 1
	graph[j][i] = 1

visit_only_once = [e for e in nodes if e.lower() == e and e != 'start' and e != 'end']

start_index = nodes.index('start')
end_index = nodes.index('end')

nodes_d = [(i,e) for i,e in enumerate(nodes)]

print(f'{nodes_d=}')
print(f'{visit_only_once=}')

visit_only_once_index = [nodes.index(e) for e in visit_only_once]+[start_index, end_index]

def explore_path(stack, level, locked, s, did_visit_twice):
	edges = [i for i,e in enumerate(graph[s]) if e]
	
	if s == end_index:
		return [s] + [stack]

	paths = []
	for edge in edges:
		if edge == start_index: continue

		if edge in visit_only_once_index:
			if edge in locked:
				if not did_visit_twice and edge != start_index and edge != end_index:
					did_visit_twice = True
				else:
					continue
			locked.add(edge)

		#print(f'{level=} , {nodes[edge]=}, {new_locked=}, {at_most=} ')
		paths += explore_path([s]+stack, level+1, locked.copy(), edge, did_visit_twice)
	return paths

print('start exploring...')

paths = explore_path([], 0, set(), start_index, False)

all_paths = [ ''.join(map(str, p)) for p in paths ]

res = list(set(all_paths))

for p in res:
	new_p = list(map(int, list(p)))
	#print([ nodes[i] for i in list(reversed(new_p))])

#print(res)

print(f'There are {len(res)} paths')