def nCr(n,r):
    a=b=1

    while r:
        a*=n; a%=Mod; n-=1
        b*=r; b%=Mod; r-=1
    return (a*pow(b,Mod-2,Mod))%Mod

a,b=map(int,input().split())
Mod=998244353
print(nCr(a+b-2,a-1))