lines = [ i.split('-') for i in open("input.txt", 'r').read().splitlines()]

paths = []

di = {}
for l in lines:
    if l[0] not in di:
        di[l[0]] = []
    di[l[0]].append(l[1])
    if l[1] not in di:
        di[l[1]] = []
    di[l[1]].append(l[0])

print(di)

def travel(stack, node):
    stack.append(node)
    if node == 'end':
        paths.append(stack.copy())
        print(stack)
    for n in di[node]:
        if n not in stack or n.isupper():
            travel(stack,n)
    stack.pop()

for start in di['start']:
    stack = ['start']
    travel(stack, start)


print(len(paths))