#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define eb emplace_back
//mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
#define mod 998244353
#define ll long long
#define inf 0x3f3f3f3f
#define INF 0x3f3f3f3f3f3f3f3f
inline int read()
{
	char ch=getchar(); int nega=1; while(!isdigit(ch)) {if(ch=='-') nega=-1; ch=getchar();}
	int ans=0; while(isdigit(ch)) {ans=ans*10+ch-48;ch=getchar();}
	if(nega==-1) return -ans;
	return ans;
}
void print(vector<int> x){for(int i=0;i<(int)x.size();i++) printf("%d%c",x[i]," \n"[i==(int)x.size()-1]);}
inline int add(int x,int y) {return x+y>=mod?x+y-mod:x+y;}
inline int add(int x,int y,int z) {return add(add(x,y),z);}
inline int sub(int x,int y) {return x-y<0?x-y+mod:x-y;}
inline int mul(int x,int y) {return 1LL*x*y%mod;}
inline int mul(int x,int y,int z) {return mul(mul(x,y),z);}
#define inc(x,y) x=add(x,y)
#define dec(x,y) x=sub(x,y)
#define MN 100005
int f[MN],g[MN],N,M,m=100;
int fac[MN],inv[MN],ifac[MN];
void init()
{
	fac[0]=1; for(int i=1;i<MN;i++) fac[i]=mul(fac[i-1],i);
	inv[0]=inv[1]=1; for(int i=2;i<MN;i++) inv[i]=mul(mod-mod/i,inv[mod%i]);
	ifac[0]=1; for(int i=1;i<MN;i++) ifac[i]=mul(ifac[i-1],inv[i]);
}
signed main()
{
	init();
	cin>>N>>M;
	f[0]=0; for(int i=1;i<=M;i++) f[i]=read();
	sort(f+1,f+M+1);
	g[0]=1;
	for(int n=0;n<=N;n++)
	{
		int res=0;
		for(int i=1;i<=M&&f[i]-1<=n;i++) inc(res,mul(f[i],g[n+1-f[i]]));
		res=mul(res,N+1);
		for(int i=1;i<=M&&f[i]<=n;i++) dec(res,mul(n-f[i]+1,g[n-f[i]+1]));
		g[n+1]=mul(res,inv[n+1]);
	}
	// cout<<g[N]<<endl;
	cout<<mul(inv[N+1],g[N])<<endl;
	return 0;
}