MOD = 998244353

n = int(input())
m = int(input())

if m > n:
  print("0")
  exit()

ans = pow(2, n, MOD)
cnt = 1
for r in range(m):
  ans = (ans - cnt) % MOD
  cnt = (cnt * (n - r)) % MOD
  cnt = (cnt * pow(r + 1, MOD - 2, MOD)) % MOD

print(ans)