#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001

mint iv[300000];
int main(){
	for(int i=1;i<300000;i++)iv[i] = mint(i).inv();
	
	int M,N;
	cin>>M>>N;
	
	vector<int> c(M);
	rep(i,N){
		int a;
		cin>>a;
		c[a-1]++;
	}
	
	vector<int> d(N+1);
	rep(i,c.size()){
		d[c[i]]++;
	}
	
	vector<mint> num(N+1,1);
	for(int i=1;i<=N;i++){
		if(d[i]==0)continue;
		mint t = 1;
		rep(j,i)t *= j+1;
		for(int j=i;j<=N;j++){
			num[j] *= t.pow(d[i]);
			t *= j+1;
			t *= iv[j-i+1];
		}
		rep(j,i)num[j] = 0;
		
	}
	vector<mint> x(N+1,0);
	x[0] = 1;
	{
		mint c = 1;
		for(int i=1;i<=N;i++){
			c /= i;
			if(i%2==0)x[i] = c;
			else x[i] = -c;
		}
	}
	{
		mint c = 1;
		for(int i=1;i<=N;i++){
			c /= i;
			num[i] *= c;
		}
	}
	x = convolution(x,num);
	mint ans= 0;
	{
		mint c = 1;
		for(int i=1;i<=N;i++){
			c *= i;
			ans += x[i]*c;
		}
	}
	
	cout<<ans.val()<<endl;
	
	return 0;
}