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