mod = 998244353

N=int(input())
M=int(input())

fac = [1]
for i in range(1,M+5):
  fac.append(fac[-1]*i%mod)
  
invfac = [1]*(M+5)
invfac[M+4] = pow(fac[M+4],mod-2,mod)
for i in range(M+3,0,-1):
  invfac[i] = invfac[i+1]*(i+1)%mod

ans = pow(2,N,mod)-1
if M > 1:
  num = N
  ans -= num
  ans %= mod
for i in range(2,M):
  num *= N-i+1
  num %= mod
  ans -= num * invfac[i]
  ans %= mod
  
print(ans)