n=int(input())
m=int(input())
mod=998244353
if n<m:exit(print(0))
ans=pow(2,n,mod)
def ncr(n, r, mod):
    ret = 1
    s=0
    inv = [1]
    for i in range(1, r+1):
        s+=ret
        s%=mod
        inv.append(max(1, (-(mod//i) * inv[mod % i]) % mod))
        ret = ret*(n+1-i)*inv[i] % mod
    return s
print((ans-max(1,ncr(n,m,mod)))%mod)