n = int(input())
m = int(input())
mod = 998244353

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