# FFT が遅い

mod = 998244353
g = 3
ginv = 332748118
W = [pow(g, (mod-1)>>i, mod) for i in range(24)]
Winv = [pow(ginv, (mod-1)>>i, mod) for i in range(24)]
 
def fft(k, f):
	for l in range(k, 0, -1):
		d = 1<<l-1
		U = [1]
		for i in range(d):
			U.append(U[-1]*W[l]%mod)
		for i in range(1<<k-l):
			for j in range(d):
				s = i*2*d+j
				f[s], f[s+d] = (f[s]+f[s+d])%mod, U[j]*(f[s]-f[s+d])%mod
 
def fftinv(k, f):
	for l in range(1, k+1):
		d = 1<<l-1
		for i in range(1<<k-l):
			u = 1
			for j in range(i*2*d, (i*2+1)*d):
				f[j+d] *= u
				f[j], f[j+d] = (f[j]+f[j+d])%mod, (f[j]-f[j+d])%mod
				u *= Winv[l]
				u %= mod
 
def convolution(a, b):
	le = len(a)+len(b)-1
	k = le.bit_length()
	n = 1<<k
	a = a+[0]*(n-len(a))
	b = b+[0]*(n-len(b))
	fft(k, a)
	fft(k, b)
	for i in range(n):
		a[i] *= b[i]
		a[i] %= mod
	fftinv(k, a)
	
	ninv = pow(n, mod-2, mod)
	for i in range(le):
		a[i] *= ninv
		a[i] %= mod
	return a[:le]


mod = 998244353
N = 10**6 + 5
fact = [1]*(N+1)
factinv = [1]*(N+1)

for i in range(2, N+1):
	fact[i] = fact[i-1] * i % mod

factinv[-1] = pow(fact[-1], mod-2, mod)
for i in range(N-1, 1, -1):
	factinv[i] = factinv[i+1] * (i+1) % mod

def cmb(a, b):
	if (a < b) or (b < 0):
		return 0
	return fact[a] * factinv[b] % mod * factinv[a-b] % mod

# ここから本編.

m,n = map(int,input().split())
a = list(map(int,input().split()))
# 頻度ごとに集計しています O(N+M)
c = [0] * m
for i in range(n):
    c[a[i]-1] += 1

cl = [0] * (n+1)
for i in range(m):
	cl[c[i]] += 1

cv = []
cmax = 0
for i in range(n+1):
	if cl[i] > 0:
		cv.append((i, cl[i]))
		cmax = max(cmax, i)

# 想定解通りにやります O(N^1.5 log N) ? わからんぬ
d = [1] * (n+1)
for i in range(n+1):
	if cmax > i:
		d[i] = 0
		continue
	for j, cnt in cv:
		d[i] *= pow(fact[i] * factinv[i-j] % mod, cnt, mod)
		d[i] %= mod

# またまたFFTによって練習の日を固定したときの数え上げを計算します O(N log N)

f = [d[i] * factinv[i] % mod for i in range(n + 1)]
g = [(-1) ** (i % 2) * factinv[i] % mod for i in range(n + 1)]
fg = convolution(f, g)

ans = 0

for i in range(n + 1):
	ans += fact[i] * fg[i] % mod

print(ans % mod)