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

mod=998244353
def  nCk(n,k):
    x,y=1,1
    for i in range(n,n-k,-1):
        x*=i
        x%=mod
    for i in range(k,0,-1):
        y*=i
        y%=mod
        
    y1=pow(y,-1,mod)
    return (x * y1)%mod

t=nCk(a-1+b-1,a-1)
print(t)