J=lambda:map(int,input().split())
N,K=J()
L=range(N)
E=[0]+[set()for i in L]
for i in L:
	u,v=J()
	E[u].add(v),E[v].add(u)
l=N
for i in L:
	r=i+1
	while len(E[r])==1:
		l,j=l-1,E[r].pop()
		E[j].remove(r)
		r=j
P=998244353
print(pow(K-1,N-l+1,P)*(pow(K-1,l-1,P)+1-l%2*2)%P)