Marshrutkas
In a modern city, private minibuses are essential for transportation. The city has a known number of routes and stops. Multiple routes may intersect at certain stops, allowing passengers to transfer between them. Your task is straightforward: find the minimum number of transfers required to travel from stop A to stop B.
**Input:** The first line contains two numbers: the total number of minibus stops in the city, N (2 ≤ N ≤ 100000), and the number of routes, M (1 ≤ M ≤ 20). The following M lines describe each route with the number of stops on that route, K (2 ≤ K_i ≤ 50), followed by the list of stop numbers for that route. The last line contains two numbers: the starting stop number A and the destination stop number B.
**Output:** Output a single number representing the minimum number of transfers needed. If it is impossible to reach stop B from stop A using only minibuses, output "Call a taxi!" (without quotes).