n = int(input()); m = int(input()); mod = 998244353
fact, inv, factinv = [1, 1], [0, 1], [1, 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)
def cmb(n, r):
    if r < 0 or n < r: return 0
    return fact[n]*factinv[r]%mod*factinv[n-r]%mod
ans = pow(2, n, mod)
for i in range(m): ans = (ans-cmb(n, i))%mod
print(ans)