def path_finder(path_graph, user_A, user_B, friend_path=[]):
    friend_path = friend_path + [user_A]
    if user_A == user_B:
        return friend_path
    if user_A not in path_graph:
        return None
    for user in path_graph[user_A]:
        if user not in friend_path:
            final_path = path_finder(path_graph, user, user_B, friend_path)
            if final_path:
                return final_path
    return None

def path_to_friend(network, user_A, user_B):
    path_graph = {}
    friend_path = []
    for user_key in network:
        path_graph[user_key] = network[user_key][0]
    path_to_friend = path_finder(path_graph, user_A, user_B, friend_path)
    return path_to_friend