#include <bits/stdc++.h>
#include <atcoder/modint>
using namespace std;
using Modint = atcoder::modint998244353;

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int N, M;
    cin >> N >> M;
    vector<int> L(M);
    for(int& l : L) cin >> l;
    sort(L.begin(), L.end());
    vector<Modint> f(N + 1);
    f[0] = 1;
    vector<Modint> inv(N + 2);
    inv[1] = 1;
    for(int i = 2; i <= N + 1; i++) inv[i] = inv[Modint::mod() % i] * -Modint::raw(Modint::mod() / i);
    for(int n = 1; n <= N; n++){
        for(int l : L){
            if(l > n) break;
            f[n] += f[n - l] * (int64_t(N) * l + l * 2 - n);
        }
        f[n] *= inv[n];
    }
    cout << (f[N] * inv[N + 1]).val() << endl;
}