n = int(input())
m = int(input())
if n < m:
  print(0)
  exit()
mod = 998244353
ans = pow(2, n, mod)
now = 1
for i in range(m):
  ans -= now
  ans %= mod
  now *= n - i
  now *= pow(i+1, mod-2, mod)
  now %= mod
print(ans)