Помогите решить задачу по информатике на питоне

 from collections import defaultdict  
  
n, m = map(int, input().split())  
  
adjacency_list = defaultdict(int)  
for _ in range(m):  
    x, y = map(int, input().split())  
    adjacency_list[x] += 1 
    adjacency_list[y] += 1 
      
degree_count = defaultdict(int)  
for node in adjacency_list: 
    degree_count[adjacency_list[node]] += 1  
  
if degree_count[2] == n - 2 and degree_count[1] == 2 and degree_count[3] == 0:  
    print("bus topology")  
elif degree_count[2] == n:  
    print("ring topology")  
elif degree_count[n - 1] == 1 and degree_count[1] == n - 1:  
    print("star topology")  
else:  
    print("unknown topology")