#define MD 998244353
int@N,@K,A[N],B[N],l;rd((A,B)(N));graph g;g.setEdge(N+1,N,A,B);Mint a=K-1;l=g.anUndirectedCycle();wt(a.pw(N-l+1)*(a.pw(l-1)+1-l%2*2));