#拡張Euclidの互除法 from collections import Counter def extgcd(a, b, d = 0): g = a if b == 0: x, y = 1, 0 else: x, y, g = extgcd(b, a % b) x, y = y, x - a // b * y return x, y, g #mod p における逆元 def invmod(a, p): x, y, g = extgcd(a, p) x %= p return x class NumberTheoreticTransform: def primitive_root(self, m): if m == 2: return 1 if m == 167772161: return 3 if m == 469762049: return 3 if m == 754974721: return 11 if m == 998244353: return 3 divs = [0] * 20 divs[0] = 2 cnt = 1 x = (m - 1) // 2 while x % 2 == 0: x //= 2 i = 3 while i ** 2 <= x: if x % i == 0: divs[cnt] = i cnt += 1 while x % i == 0: x //= i if x > 1: divs[cnt] = x cnt += 1 g = 2 while True: f = True for i in range(cnt): if pow(g, (m - 1) // divs[i], m) == 1: break else: return g g += 1 def bsf(self, x): res = 0 while x % 2 == 0: res += 1 x //= 2 return res def __init__(self, mod): self.mod = mod self.g = self.primitive_root(self.mod) def butterfly(self, a): n = len(a) h = (n - 1).bit_length() sum_e = (911660635, 509520358, 369330050, 332049552, 983190778, 123842337, 238493703, 975955924, 603855026, 856644456, 131300601, 842657263, 730768835, 942482514, 806263778, 151565301, 510815449, 503497456, 743006876, 741047443, 56250497) for ph in range(1, h + 1): w = 1 << (ph - 1) p = 1 << (h - ph) now = 1 for s in range(w): offset = s << (h - ph + 1) for i in range(p): l = a[i + offset] r = a[i + offset + p] * now % self.mod a[i + offset] = (l + r) % self.mod a[i + offset + p] = (l - r) % self.mod now = now * sum_e[(~s & -~s).bit_length() - 1] % self.mod def butterfly_inv(self, a): n = len(a) h = (n - 1).bit_length() sum_ie = (86583718, 372528824, 373294451, 645684063, 112220581, 692852209, 155456985, 797128860, 90816748, 860285882, 927414960, 354738543, 109331171, 293255632, 535113200, 308540755, 121186627, 608385704, 438932459, 359477183, 824071951) for ph in range(h, 0, -1): w = 1 << (ph - 1) p = 1 << (h - ph) inow = 1 for s in range(w): offset = s << (h - ph + 1) for i in range(p): l = a[i + offset] r = a[i + offset + p] a[i + offset] = (l + r) % self.mod a[i + offset + p] = (l - r) * inow % self.mod inow = inow * sum_ie[(~s & -~s).bit_length() - 1] % self.mod def convolution(self, a, b): n = len(a) m = len(b) if not a or not b: return [] z = 1 << (n + m - 2).bit_length() a += [0] * (z - n) b += [0] * (z - m) self.butterfly(a) self.butterfly(b) c = [0] * z for i in range(z): c[i] = a[i] * b[i] % self.mod self.butterfly_inv(c) iz = invmod(z, self.mod) for i in range(n + m - 1): c[i] = c[i] * iz % self.mod return c[:n + m - 1] class FormalPowerSeries: def __init__(self, n, l = [], mod = 998244353): self.n = n self.l = l + [0] * (n - len(l)) self.mod = mod def add(self, other): res = FormalPowerSeries(self.n, [], self.mod) for i in range(self.n): res.l[i] = self.l[i] + other.l[i] res.l[i] %= self.mod return res def subtract(self, other): res = FormalPowerSeries(self.n, [], self.mod) for i in range(self.n): res.l[i] = self.l[i] - other.l[i] res.l[i] %= self.mod return res def multiply(self, other): res = FormalPowerSeries(self.n * 2, [], self.mod) NTT = NumberTheoreticTransform(self.mod) cv = NTT.convolution(self.l, other.l) for i in range(len(cv)): res.l[i] = cv[i] return res def resize(self, n): res = FormalPowerSeries(n, [], self.mod) for i in range(min(n, self.n)): res.l[i] = self.l[i] return res def times(self, k): res = FormalPowerSeries(self.n, [], self.mod) for i in range(self.n): res.l[i] = self.l[i] * k % self.mod return res def inverse(self): r = invmod(self.l[0], self.mod) m = 1 res = FormalPowerSeries(m, [r], self.mod) while m < self.n: m *= 2 res = res.resize(m) res = res.times(2).subtract(res.multiply(res.resize(m)).multiply(self.resize(m))) res = res.resize(self.n) return res def divide(self, other): self.multiply(self, other.inverse()) def differentiate(self): res = FormalPowerSeries(self.n, [], self.mod) for i in range(1, self.n): res.l[i - 1] = self.l[i] * i % self.mod return res def integrate(self): res = FormalPowerSeries(self.n, [], self.mod) for i in range(self.n - 1): res.l[i + 1] = self.l[i] * invmod(i + 1, self.mod) return res n, x = map(int, input().split()) a = list(map(int, input().split())) d = dict(Counter(a)) l = [0] * (10 ** 5 + 10) for k, v in d.items(): l[k] = v a = FormalPowerSeries(10 ** 5 + 10, l) print(a.multiply(a.resize(10 ** 5 + 10)).l[x])