//g++ 3.cpp -std=c++14 -O2 -I .
#include <bits/stdc++.h>
using namespace std;

#include <atcoder/all>
using namespace atcoder;

using ll = long long;
using ld = long double;

using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vld = vector<ld>;
using vvld = vector<vld>;
using vst = vector<string>;
using vvst = vector<vst>;

#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define pq_big(T) priority_queue<T,vector<T>,less<T>>
#define pq_small(T) priority_queue<T,vector<T>,greater<T>>
#define all(a) a.begin(),a.end()
#define rep(i,start,end) for(ll i=start;i<(ll)(end);i++)
#define per(i,start,end) for(ll i=start;i>=(ll)(end);i--)
#define uniq(a) sort(all(a));a.erase(unique(all(a)),a.end())

using mint = modint998244353;
constexpr ll mod = 998244353;

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  ll n,m;
  cin>>n>>m;

  ll mx=min(n,m+1);

  mint pw[mx+1][n+1]={}; // pw[i][j] := (M+1-i)^(N-k)
  rep(i,0,mx+1){
    pw[i][n]=1;
    per(j,n-1,0){
      pw[i][j]=pw[i][j+1]*(m+1-i);
    }
  }

  mint pw2[n+1]={}; // pw2[i] := 2^i
  pw2[0]=1;
  rep(i,1,n+1){
    pw2[i]=pw2[i-1]*2;
  }

  mint fac[n+1]={}; // fac[i] := i!
  fac[0]=1;
  rep(i,1,n+1){
    fac[i]=fac[i-1]*i;
  }

  vll fp(n+1,0);
  rep(i,1,n+1){
    mint now=pw2[i]-1;
    now/=(pw2[i]*fac[i]);
    fp[i]=now.val();
  }

  mint ans=0;

  vll fp_now={1};

  rep(i,1,mx+1){
    fp_now=convolution(fp_now,fp);
    rep(j,0,n+1){
      mint now=1;
      now/=fac[n-j];
      now*=pw[i][j];
      now*=fp_now[j];

      ans+=now;
    }

    while(fp_now.size()>n+5){
      fp_now.pop_back();
    }
  }

  ans*=pw2[n];
  ans*=fac[n];

  cout<<ans.val()<<endl;
}