a,b=map(int,input().split())
MOD=998244353

def combo(n, k):
    def fact(n,k=0):
        a=1
        for i in range(k+1,n+1):
            a=a * i % MOD
        return a
    k=min(k,n-k)
    a=fact(n, n-k)
    b=fact(k)
    return (a * pow(b, MOD-2, MOD)) % MOD

print(combo(a+b-2,a-1))