MOD = 998244353
N,K = map(int,input().split())

fact = [1]*(N+1)
rfact = [1]*(N+1)
r = 1
for i in range(1, N+1):
    fact[i] = r = r * i % MOD
rfact[N] = r = pow(fact[N], MOD-2, MOD)
for i in range(N, 0, -1):
    rfact[i-1] = r = r * i % MOD

def comb(n, k):
    return fact[n] * rfact[k] * rfact[n-k] % MOD

ans = 0
for i in range(1,N):
    ans += pow(i,K,MOD) * comb(N-1,i)
    ans %= MOD
print(ans)