n,c=map(int,input().split())
edge=[]
for _ in range(n-1):
  a,b=map(int,input().split())
  a-=1
  b-=1
  edge.append((a,b))
ans=0
for i in range(c**n):
  color=[]
  for j in range(n):
    color.append(i%c)
    i//=c
  flag=True
  for a,b in edge:
    if abs(color[a]-color[b])!=3:flag=False
  ans+=flag
print(ans)