graph = {'A': set(['B', 'C']),
'B': set(['A', 'D', 'E']),
'C': set(['A', 'F']),
'D': set(['B']),
'E': set(['B', 'F']),
'F': set(['C', 'E'])}
start, end = [i for i in input().split()]
queue = [start]
visited = [start]
def solution():
count = -1
while len(queue)!=0:
count += 1
size = len(queue)
for i in range(size):
node = queue.pop(0)
if node == end:
return count
for next_node in graph[node]:
if next_node not in visited:
visited.append(next_node)
queue.append(next_node)
print(solution())