#include <cstdio>
#include <algorithm>
const int Maxn=100000;
const int Maxm=100;
const int Mod=998244353;
int n,m;
int l[Maxm+5];
int f[Maxn+5],inv[Maxn+5];
int main(){
	scanf("%d%d",&n,&m);
	inv[0]=inv[1]=1;
	for(int i=2;i<=n+1;i++){
		inv[i]=1ll*(Mod-Mod/i)*inv[Mod%i]%Mod;
	}
	for(int i=1;i<=m;i++){
		scanf("%d",&l[i]);
	}
	std::sort(l+1,l+1+m);
	f[0]=1;
	for(int i=0;i<n;i++){
		int sum=0;
		for(int j=1;j<=m&&l[j]-1<=i;j++){
			sum=(sum+1ll*l[j]*f[i-(l[j]-1)])%Mod;
		}
		sum=1ll*sum*(n+1)%Mod;
		for(int j=1;j<=m&&l[j]<=i;j++){
			sum=(sum+1ll*(Mod-f[i-l[j]+1])*(i-l[j]+1))%Mod;
		}
		f[i+1]=1ll*sum*inv[i+1]%Mod;
	}
	int ans=1ll*f[n]*inv[n+1]%Mod;
	printf("%d\n",ans);
	return 0;
}