n,k=map(int,input().split())
M=998244353
e=[[] for i in range(n)]
d=[0]*n
for i in range(n):
  a,b=map(int,input().split())
  a-=1
  b-=1
  e[a]+=[b]
  e[b]+=[a]
  d[a]+=1
  d[b]+=1

v=[d[i]==1 for i in range(n)]
q=[i for i in range(n) if d[i]==1]

for s in q:
  for t in e[s]:
    d[t]-=1
    if d[t]==1 and v[t]==0:
      v[t]=1
      q+=[t]

q1=[0,0]
q2=[0,k]
for i in range(2,n+2):
  q1+=[(q1[i-1]*(k-2)+q2[i-1]*(k-1))%M]
  q2+=[q1[i-1]]

l=n-sum(v)
print(q2[l+1]*pow(k-1,n-l,M)%M)