using System; using System.Collections.Generic; using System.IO; using System.Linq; using static System.Math; using System.Text; using System.Threading; using System.Globalization; using System.Runtime.CompilerServices; using Library; namespace Program { public static class ProblemA { static bool SAIKI = false; static public int numberOfRandomCases = 0; static public void MakeTestCase(List _input, List _output, ref Func _outputChecker) { } static public void Solve() { var N = NN; var K = NN; LIB_Mod._mod = 998244353; LIB_Mod ans = 0; var stirling = LIB_Mod.LIB_StirlingSecond(N, K); for (var i = 0; i < K; i++) { if (i % 2 == 0) continue; var pat = LIB_Mod.Comb(K, i); var hakoCnt = K - i; if (hakoCnt > N) continue; ans += pat * stirling[hakoCnt] * LIB_Mod.Perm(hakoCnt,hakoCnt); } Console.WriteLine(ans); } class Printer : StreamWriter { public override IFormatProvider FormatProvider { get { return CultureInfo.InvariantCulture; } } public Printer(Stream stream) : base(stream, new UTF8Encoding(false, true)) { base.AutoFlush = false; } public Printer(Stream stream, Encoding encoding) : base(stream, encoding) { base.AutoFlush = false; } } static LIB_FastIO fastio = new LIB_FastIODebug(); static public void Main(string[] args) { if (args.Length == 0) { fastio = new LIB_FastIO(); Console.SetOut(new Printer(Console.OpenStandardOutput())); } if (SAIKI) { var t = new Thread(Solve, 134217728); t.Start(); t.Join(); } else Solve(); Console.Out.Flush(); } static long NN => fastio.Long(); static double ND => fastio.Double(); static string NS => fastio.Scan(); static long[] NNList(long N) => Repeat(0, N).Select(_ => NN).ToArray(); static double[] NDList(long N) => Repeat(0, N).Select(_ => ND).ToArray(); static string[] NSList(long N) => Repeat(0, N).Select(_ => NS).ToArray(); static long Count(this IEnumerable x, Func pred) => Enumerable.Count(x, pred); static IEnumerable Repeat(T v, long n) => Enumerable.Repeat(v, (int)n); static IEnumerable Range(long s, long c) => Enumerable.Range((int)s, (int)c); static IOrderedEnumerable OrderByRand(this IEnumerable x) => Enumerable.OrderBy(x, _ => xorshift); static IOrderedEnumerable OrderBy(this IEnumerable x) => Enumerable.OrderBy(x.OrderByRand(), e => e); static IOrderedEnumerable OrderBy(this IEnumerable x, Func selector) => Enumerable.OrderBy(x.OrderByRand(), selector); static IOrderedEnumerable OrderByDescending(this IEnumerable x) => Enumerable.OrderByDescending(x.OrderByRand(), e => e); static IOrderedEnumerable OrderByDescending(this IEnumerable x, Func selector) => Enumerable.OrderByDescending(x.OrderByRand(), selector); static IOrderedEnumerable OrderBy(this IEnumerable x) => x.OrderByRand().OrderBy(e => e, StringComparer.OrdinalIgnoreCase); static IOrderedEnumerable OrderBy(this IEnumerable x, Func selector) => x.OrderByRand().OrderBy(selector, StringComparer.OrdinalIgnoreCase); static IOrderedEnumerable OrderByDescending(this IEnumerable x) => x.OrderByRand().OrderByDescending(e => e, StringComparer.OrdinalIgnoreCase); static IOrderedEnumerable OrderByDescending(this IEnumerable x, Func selector) => x.OrderByRand().OrderByDescending(selector, StringComparer.OrdinalIgnoreCase); static uint xorshift { get { _xsi.MoveNext(); return _xsi.Current; } } static IEnumerator _xsi = _xsc(); static IEnumerator _xsc() { uint x = 123456789, y = 362436069, z = 521288629, w = (uint)(DateTime.Now.Ticks & 0xffffffff); while (true) { var t = x ^ (x << 11); x = y; y = z; z = w; w = (w ^ (w >> 19)) ^ (t ^ (t >> 8)); yield return w; } } } } namespace Library { class LIB_NTT { uint mod; uint root; [MethodImpl(MethodImplOptions.AggressiveInlining)] LIB_NTT(uint mod, uint root) { this.mod = mod; this.root = root; } [MethodImpl(MethodImplOptions.AggressiveInlining)] uint add(uint x, uint y) => (x + y < mod) ? (x + y) : (x + y - mod); [MethodImpl(MethodImplOptions.AggressiveInlining)] uint sub(uint x, uint y) => (x >= y) ? (x - y) : (mod - y + x); [MethodImpl(MethodImplOptions.AggressiveInlining)] uint mul(uint x, uint y) => (uint)((ulong)x * y % mod); [MethodImpl(MethodImplOptions.AggressiveInlining)] uint pow(uint x, uint n) { uint res = 1; while (n > 0) { if ((n & 1) != 0) res = mul(res, x); x = mul(x, x); n >>= 1; } return res; } [MethodImpl(MethodImplOptions.AggressiveInlining)] uint inverse(uint x) { long b = mod, r = 1, u = 0, t = 0, x2 = x; while (b > 0) { var q = x2 / b; t = u; u = r - q * u; r = t; t = b; b = x2 - q * b; x2 = t; } return (uint)(r < 0 ? r + mod : r); } [MethodImpl(MethodImplOptions.AggressiveInlining)] void ntt(ref uint[] a, bool rev = false) { var n = (uint)a.Length; if (n == 1) return; var b = new uint[n]; var s = pow(root, rev ? (mod - 1 - (mod - 1) / n) : (mod - 1) / n); var kp = Enumerable.Repeat((uint)1, (int)(n / 2 + 1)).ToArray(); uint i, j, k, l, r; for (i = 0; i < n / 2; ++i) kp[i + 1] = mul(kp[i], s); for (i = 1, l = n / 2; i < n; i <<= 1, l >>= 1) { for (j = 0, r = 0; j < l; ++j, r += i) { for (k = 0, s = kp[i * j]; k < i; ++k) { var p = a[k + r]; var q = a[k + r + n / 2]; b[k + 2 * r] = add(p, q); b[k + 2 * r + i] = mul(sub(p, q), s); } } var t = a; a = b; b = t; } if (rev) { s = inverse(n); for (i = 0; i < n; ++i) a[i] = mul(a[i], s); } } [MethodImpl(MethodImplOptions.AggressiveInlining)] static uint[] Multiply(uint[] a, uint[] b, uint mod, uint root) { var n = a.Length + b.Length - 1; var t = 1; while (t < n) t <<= 1; var na = new uint[t]; var nb = new uint[t]; for (var i = 0; i < a.Length; ++i) na[i] = a[i]; for (var i = 0; i < b.Length; ++i) nb[i] = b[i]; var ntt = new LIB_NTT(mod, root); ntt.ntt(ref na); ntt.ntt(ref nb); for (var i = 0; i < t; ++i) na[i] = ntt.mul(na[i], nb[i]); ntt.ntt(ref na, true); return na.Take(n).ToArray(); } [MethodImpl(MethodImplOptions.AggressiveInlining)] static public long[] Multiply(long[] a, long[] b) => Multiply(a.Select(e => (uint)e).ToArray(), b.Select(e => (uint)e).ToArray(), 998244353, 3).Select(e => (long)e).ToArray(); [MethodImpl(MethodImplOptions.AggressiveInlining)] static public long[] Multiply(long[] a, long[] b, long mod) { if (mod == 998244353) return Multiply(a, b); var m1 = new LIB_NTT(1045430273, 3); var m2 = new LIB_NTT(1051721729, 6); var m3 = new LIB_NTT(1053818881, 7); var uinta = a.Select(e => (uint)e).ToArray(); var uintb = b.Select(e => (uint)e).ToArray(); var x = Multiply(uinta, uintb, m1.mod, m1.root); var y = Multiply(uinta, uintb, m2.mod, m2.root); var z = Multiply(uinta, uintb, m3.mod, m3.root); var m1_inv_m2 = m2.inverse(m1.mod); var m12_inv_m3 = m3.inverse(m3.mul(m1.mod, m2.mod)); var m12_mod = (long)m1.mod * m2.mod % mod; var ret = new long[x.Length]; for (var i = 0; i < x.Length; ++i) { var v1 = m2.mul(m2.sub(m2.add(y[i], m2.mod), x[i]), m1_inv_m2); var v2 = m3.mul(m3.sub(m3.sub(m3.add(z[i], m3.mod), x[i]), m3.mul(m1.mod, v1)), m12_inv_m3); ret[i] = (x[i] + ((long)m1.mod * v1 % mod) + ((long)m12_mod * v2 % mod)) % mod; } return ret; } } partial struct LIB_Mod : IEquatable, IEquatable { static public long _mod = 1000000007; long v; [MethodImpl(MethodImplOptions.AggressiveInlining)] public LIB_Mod(long x) { if (x < _mod && x >= 0) v = x; else if ((v = x % _mod) < 0) v += _mod; } [MethodImpl(MethodImplOptions.AggressiveInlining)] static public implicit operator LIB_Mod(long x) => new LIB_Mod(x); [MethodImpl(MethodImplOptions.AggressiveInlining)] static public implicit operator long(LIB_Mod x) => x.v; [MethodImpl(MethodImplOptions.AggressiveInlining)] public void Add(LIB_Mod x) { if ((v += x.v) >= _mod) v -= _mod; } [MethodImpl(MethodImplOptions.AggressiveInlining)] public void Sub(LIB_Mod x) { if ((v -= x.v) < 0) v += _mod; } [MethodImpl(MethodImplOptions.AggressiveInlining)] public void Mul(LIB_Mod x) => v = (v * x.v) % _mod; [MethodImpl(MethodImplOptions.AggressiveInlining)] public void Div(LIB_Mod x) => v = (v * Inverse(x.v)) % _mod; [MethodImpl(MethodImplOptions.AggressiveInlining)] static public LIB_Mod operator +(LIB_Mod x, LIB_Mod y) { var t = x.v + y.v; return t >= _mod ? new LIB_Mod { v = t - _mod } : new LIB_Mod { v = t }; } [MethodImpl(MethodImplOptions.AggressiveInlining)] static public LIB_Mod operator -(LIB_Mod x, LIB_Mod y) { var t = x.v - y.v; return t < 0 ? new LIB_Mod { v = t + _mod } : new LIB_Mod { v = t }; } [MethodImpl(MethodImplOptions.AggressiveInlining)] static public LIB_Mod operator *(LIB_Mod x, LIB_Mod y) => x.v * y.v; [MethodImpl(MethodImplOptions.AggressiveInlining)] static public LIB_Mod operator /(LIB_Mod x, LIB_Mod y) => x.v * Inverse(y.v); [MethodImpl(MethodImplOptions.AggressiveInlining)] static public bool operator ==(LIB_Mod x, LIB_Mod y) => x.v == y.v; [MethodImpl(MethodImplOptions.AggressiveInlining)] static public bool operator !=(LIB_Mod x, LIB_Mod y) => x.v != y.v; [MethodImpl(MethodImplOptions.AggressiveInlining)] static public long Inverse(long x) { long b = _mod, r = 1, u = 0, t = 0; while (b > 0) { var q = x / b; t = u; u = r - q * u; r = t; t = b; b = x - q * b; x = t; } return r < 0 ? r + _mod : r; } [MethodImpl(MethodImplOptions.AggressiveInlining)] public bool Equals(LIB_Mod x) => v == x.v; [MethodImpl(MethodImplOptions.AggressiveInlining)] public bool Equals(long x) => v == x; [MethodImpl(MethodImplOptions.AggressiveInlining)] public override bool Equals(object x) => x == null ? false : Equals((LIB_Mod)x); [MethodImpl(MethodImplOptions.AggressiveInlining)] public override int GetHashCode() => v.GetHashCode(); [MethodImpl(MethodImplOptions.AggressiveInlining)] public override string ToString() => v.ToString(); static List _fact = new List() { 1 }; static long _factm = _mod; [MethodImpl(MethodImplOptions.AggressiveInlining)] static void B(long n) { if (_factm != _mod) _fact = new List() { 1 }; if (n >= _fact.Count) for (int i = _fact.Count; i <= n; ++i) _fact.Add(_fact[i - 1] * i); _factm = _mod; } [MethodImpl(MethodImplOptions.AggressiveInlining)] static public LIB_Mod Comb(long n, long k) { B(n); if (n == 0 && k == 0) return 1; if (n < k || n < 0) return 0; return _fact[(int)n] / _fact[(int)(n - k)] / _fact[(int)k]; } [MethodImpl(MethodImplOptions.AggressiveInlining)] static public LIB_Mod CombOK(long n, long k) { LIB_Mod ret = 1; for (var i = 0; i < k; i++) ret *= n - i; for (var i = 1; i <= k; i++) ret /= i; return ret; } [MethodImpl(MethodImplOptions.AggressiveInlining)] static public LIB_Mod Perm(long n, long k) { B(n); if (n == 0 && k == 0) return 1; if (n < k || n < 0) return 0; return _fact[(int)n] / _fact[(int)(n - k)]; } [MethodImpl(MethodImplOptions.AggressiveInlining)] static public LIB_Mod Pow(LIB_Mod x, long y) { LIB_Mod a = 1; while (y != 0) { if ((y & 1) == 1) a.Mul(x); x.Mul(x); y >>= 1; } return a; } } class LIB_FastIO { [MethodImpl(MethodImplOptions.AggressiveInlining)] public LIB_FastIO() { str = Console.OpenStandardInput(); } readonly Stream str; readonly byte[] buf = new byte[1024]; int len, ptr; public bool isEof = false; public bool IsEndOfStream { [MethodImpl(MethodImplOptions.AggressiveInlining)] get { return isEof; } } [MethodImpl(MethodImplOptions.AggressiveInlining)] byte read() { if (isEof) throw new EndOfStreamException(); if (ptr >= len) { ptr = 0; if ((len = str.Read(buf, 0, 1024)) <= 0) { isEof = true; return 0; } } return buf[ptr++]; } [MethodImpl(MethodImplOptions.AggressiveInlining)] char Char() { byte b = 0; do b = read(); while (b < 33 || 126 < b); return (char)b; } [MethodImpl(MethodImplOptions.AggressiveInlining)] virtual public string Scan() { var sb = new StringBuilder(); for (var b = Char(); b >= 33 && b <= 126; b = (char)read()) sb.Append(b); return sb.ToString(); } [MethodImpl(MethodImplOptions.AggressiveInlining)] virtual public long Long() { long ret = 0; byte b = 0; var ng = false; do b = read(); while (b != '-' && (b < '0' || '9' < b)); if (b == '-') { ng = true; b = read(); } for (; true; b = read()) { if (b < '0' || '9' < b) return ng ? -ret : ret; else ret = ret * 10 + b - '0'; } } [MethodImpl(MethodImplOptions.AggressiveInlining)] virtual public double Double() { return double.Parse(Scan(), CultureInfo.InvariantCulture); } } class LIB_FastIODebug : LIB_FastIO { Queue param = new Queue(); [MethodImpl(MethodImplOptions.AggressiveInlining)] string NextString() { if (param.Count == 0) foreach (var item in Console.ReadLine().Split(' ')) param.Enqueue(item); return param.Dequeue(); } [MethodImpl(MethodImplOptions.AggressiveInlining)] public LIB_FastIODebug() { } [MethodImpl(MethodImplOptions.AggressiveInlining)] public override string Scan() => NextString(); [MethodImpl(MethodImplOptions.AggressiveInlining)] public override long Long() => long.Parse(NextString()); [MethodImpl(MethodImplOptions.AggressiveInlining)] public override double Double() => double.Parse(NextString()); } /// copy key class LIB_StirlingSecond partial struct /* not copy key */ LIB_Mod { [MethodImpl(MethodImplOptions.AggressiveInlining)] static public LIB_Mod[] LIB_StirlingSecond(long n, long k) { var a = new LIB_Mod[k + 1]; for (var i = 0; i <= k; i++) a[i] = (i % 2 == 1 ? -1 : 1) / Perm(i, i); var b = new LIB_Mod[k + 1]; for (var i = 0; i <= k; i++) b[i] = Pow(i, n) / Perm(i, i); return LIB_NTT.Multiply(a.Select(e => (long)e).ToArray(), b.Select(e => (long)e).ToArray(), _mod).Take((int)k + 1).Select(e => (LIB_Mod)e).ToArray(); } } }