#include <bits/stdc++.h>
using namespace std;

#define REP(i,n) for(int i=0;i<(n);i++)

#include <atcoder/modint>
using namespace atcoder;
using mint=modint998244353;
ostream& operator<<(ostream &os,mint a){os<<a.val();return os;}
istream& operator>>(istream &is,mint &a){
  long long b;is>>b;a=b;
  return is;
}

const int SIZE=5000000;
mint Factorial[SIZE],Finverse[SIZE];
void Cinit(){
  Factorial[0]=mint(1);
  for(int i=1;i<SIZE;i++)Factorial[i]=Factorial[i-1]*mint(i);
  Finverse[SIZE-1]=Factorial[SIZE-1].inv();
  for(int i=SIZE-2;i>=0;i--)Finverse[i]=mint(i+1)*Finverse[i+1];
}
mint nCk(int n,int k){
  if(Factorial[0]==0)Cinit();
  if(n<k)return 0;
  return Factorial[n]*Finverse[n-k]*Finverse[k];
}

int main(){
  int n,k;cin>>n>>k;
  mint ans=mint(k).pow(n);
  REP(i,k+1)ans-=mint(k-i).pow(n)*mint(-2).pow(i)*nCk(k,i);
  ans/=2;
  cout<<ans<<endl;
}