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

int main(){
    int n, m; cin >> n >> m;
    vector<int> l(m); rep(i,m) cin >> l[i];
    vector<mint> dp(n+1,0);
    dp[0] = 1;
    repp(i,n+1,1){
        rep(j,m) if (i - l[j] >= 0) dp[i] += (mint(n+2) * mint(l[j]) - mint(i)) * dp[i-l[j]];
        dp[i] /= i;
    }
    mint ans = dp[n] / mint(n+1);
    cout << ans.val() << endl;
}