#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int INF = (1<<30)-1;
const ll LINF = (1LL<<60)-1;

#define rep(i, n) for (int i = 0; i < n; i++)
#define sz(a) (int)(a.size())

template<class T> 
bool chmax(T &a, T b) {if (a < b) {a = b;return true;}else return false;}

template<class T> 
bool chmin(T &a, T b) {if (a > b) {a = b;return true;}else return false;}

ll mod_pow(ll a, ll n, ll p) {
    ll  ans = 1, tmp = a % p;
    while (n > 0) {
        if (n & 1)
            ans = ans * tmp % p;
        tmp = tmp * tmp % p;
        n = (n>>1);
    }
    return ans;
}

//コーナーケースに気をつけろ！
int main() {
    ll n, m, mod = 998244353, ans = 0, tmp = 0;    cin >> n >> m;
    ans = n * mod_pow(m, n, mod) % mod;

    for (ll l = 1; l <= n-1; l++) {
        for (ll x = 1; x <= m; x++) {
            tmp = (tmp + (n-l) * mod_pow(m, n-l-1, mod) % mod * mod_pow(m-x, l-1, mod) % mod) % mod;
        }
    }
    cout << (ans + mod - tmp) % mod << endl;
    return 0;
}

//小数点精度
//cout << fixed << std::setprecision(15) << y << endl;
#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;

//template
#define rep(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define ALL(v) (v).begin(),(v).end()
using ll=long long int;
const int inf = 0x3fffffff; const ll INF = 0x1fffffffffffffff; const double eps=1e-12;
template<typename T>inline bool chmax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
template<typename T>inline bool chmin(T& a,T b){if(a>b){a=b;return 1;}return 0;}
//end

struct UnionFind{
   vector<int> par; int n;
   UnionFind(){}
   UnionFind(int _n):par(_n,-1),n(_n){}
   int root(int x){return par[x]<0?x:par[x]=root(par[x]);}
   bool same(int x,int y){return root(x)==root(y);}
   int size(int x){return -par[root(x)];}
   bool unite(int x,int y){
      x=root(x),y=root(y); if(x==y)return false;
      if(size(x)>size(y))swap(x,y);
      par[y]+=par[x]; par[x]=y; n--; return true;
   }
};

template<unsigned mod=998244353>struct fp {
   using uint=unsigned; uint v;
   static uint get_mod(){return mod;}
   int inv() const{
      int tmp,a=v,b=mod,x=1,y=0;
      while(b)tmp=a/b,a-=tmp*b,swap(a,b),x-=tmp*y,swap(x,y);
      if(x<0){x+=mod;} return x;
   }
   fp(ll x=0){init(x%mod+mod);}
   fp& init(uint x){v=(x<mod?x:x-mod); return *this;}
   fp operator-()const{return fp()-*this;}
   fp pow(ll t){fp res=1,b=*this; while(t){if(t&1)res*=b;b*=b;t>>=1;} return res;}
   fp& operator+=(const fp& x){return init(v+x.v);}
   fp& operator-=(const fp& x){return init(v+mod-x.v);}
   fp& operator*=(const fp& x){v=ll(v)*x.v%mod; return *this;}
   fp& operator/=(const fp& x){v=ll(v)*x.inv()%mod; return *this;}
   fp operator+(const fp& x)const{return fp(*this)+=x;}
   fp operator-(const fp& x)const{return fp(*this)-=x;}
   fp operator*(const fp& x)const{return fp(*this)*=x;}
   fp operator/(const fp& x)const{return fp(*this)/=x;}
   bool operator==(const fp& x)const{return v==x.v;}
   bool operator!=(const fp& x)const{return v!=x.v;}
   friend istream& operator>>(istream& is,fp& x){is>>x.v; return is;}
   friend ostream& operator<<(ostream& os,fp& x){os<<x.v; return os;}
}; using Fp=fp<>;
template<typename T>struct factorial {
   vector<T> Fact,Finv,Inv;
   factorial(int maxx){
      Fact.resize(maxx); Finv.resize(maxx); Inv.resize(maxx);
      Fact[0]=Fact[1]=Finv[0]=Finv[1]=Inv[1]=1;
      rep(i,2,maxx){Fact[i]=Fact[i-1]*i;} Finv[maxx-1]=Fact[maxx-1].inv();
      for(int i=maxx-1;i>=2;i--){Finv[i-1]=Finv[i]*i; Inv[i]=Finv[i]*Fact[i-1];}
   }
   T fact(int n,bool inv=0){if(n<0)return 0; return (inv?Finv[n]:Fact[n]);}
   T inv(int n){if(n<0)return 0; return Inv[n];}
   T nPr(int n,int r,bool inv=0){if(n<0||n<r||r<0)return 0; return fact(n,inv)*fact(n-r,inv^1);}
   T nCr(int n,int r,bool inv=0){if(n<0||n<r||r<0)return 0; return fact(n,inv)*fact(r,inv^1)*fact(n-r,inv^1);}
};

Fp pre[5010][5010];

int main(){
   int n,m;
   cin>>n>>m;
   rep(x,1,5005){
      pre[x][0]=1;
      rep(t,0,5005)pre[x][t+1]=pre[x][t]*x;
   }

   Fp res;
   rep(len,1,n+1)rep(v,1,m+1){
      if(len==n){
         res+=(pre[m-v+1][n]-pre[m-v][n]);
         continue;
      }
      res+=(pre[m-v+1][len]-pre[m-v][len])*(v-1)*pre[m][max(0,n-len-1)]*2;
      res+=(pre[m-v+1][len]-pre[m-v][len])*(v-1)*(v-1)*pre[m][max(0,n-len-2)]*max(0,n-len-1);
   }
   cout<<res<<'\n';
   return 0;
}