#include <cstdio>
const long long mod = 998244353;

long long power(long long a,long long b){
	long long res = 1;
	while(b){
		if(b&1) res = res * a%mod;
		a = a*a%mod;
		b /= 2;
	}
	return res;
}

long long NotBigger(long long k,long long n){
	long long digit = (1+k)*k/2%mod;
	n = n%mod;
	return digit*(n%mod)%mod;
}

long long inRange(long long l,long long r,long long n){
	if(l>r) return 0;
	long long digit = (l+r)*(r-l+1)/2%mod;
	long long gap = r-l+1;
	long long res =  digit*power(gap,n-1)%mod;
	res = res*(n%mod)%mod;
	return res;
}

int main(){
	long long n,m;
	scanf("%lld%lld",&n,&m);
	long long pos = 0, neg = 0;
	for(int i = 1; i <= m; i++){
		long long way = inRange(1,i,n);
		way = way - inRange(1,i-1,n);
		if(way < 0) way += mod;
		//printf("pway = %lld\n",way);
		pos = (pos + way * (long long)i%mod)%mod;
		way = inRange(i,m,n);
		way = way - inRange(i+1,m,n);
		if(way < 0) way += mod;
		//printf("nway = %lld\n",way);
		neg = (neg + way * (long long)i%mod)%mod;
	}
	//printf("pos = %lld, neg = %lld\n",pos,neg);
	long long ans = pos - neg;
	if(ans < 0) ans += mod;
	printf("%lld\n",ans);
	return 0;
}