N=int(input())
M=int(input())
mod=998244353
def xgcd(a, b):
    x0, y0, x1, y1 = 1, 0, 0, 1
    while b != 0:
        q, a, b = a // b, b, a % b
        x0, x1 = x1, x0 - q * x1
        y0, y1 = y1, y0 - q * y1
    return a, x0, y0

def modinv(a, m):
    g, x, y = xgcd(a, m)
    if g != 1:
        raise Exception('modular inverse does not exist')
    else:
        return x % m
gt=modinv(3,mod)
c=1
ans=1
for i in range(1,M):
  c*=(N+1-i)
  c%=mod
  c*=modinv(i,mod)
  ans+=c
print((pow(2,N,mod)-ans)%mod)