import sys
sys.setrecursionlimit(5*10**5)
input = sys.stdin.readline
import pypyjit
pypyjit.set_param('max_unroll_recursion=-1')
from collections import defaultdict, deque, Counter
from heapq import heappop, heappush
from bisect import bisect_left, bisect_right
from math import gcd
mod = 998244353

n = int(input())
m = int(input())
ans = pow(2, n, mod) - 1
if m > n:
  print(0)
  exit()
#nCk
def com(n,mod):
  fact = [1,1]
  factinv = [1,1]
  inv = [0,1]
  for i in range(2,n+1):
    fact.append((fact[-1]*i)%mod)
    inv.append((-inv[mod%i]*(mod//i))%mod)
    factinv.append((factinv[-1]*inv[-1])%mod)
  return fact, factinv

f,fi = com(m+10, mod)

ue = n

for i in range(1,m):
  tmp = ue * fi[i] % mod
  ans -= tmp
  ans %= mod
  ue *= n-i
  ue %= mod

print(ans)