#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>

#define ll long long
#define pb push_back
#define sz(x) (int)(x).size()
#define mp make_pair
#define f first
#define s second
#define all(x) x.begin(), x.end()
#define D(x) cerr << #x << " is " << (x) << "\n";

using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;

template<class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>; ///find_by_order(),order_of_key()
template<class T1, class T2> ostream& operator<<(ostream& os, const pair<T1,T2>& a) { os << '{' << a.f << ", " << a.s << '}'; return os; }
template<class T> ostream& operator<<(ostream& os, const vector<T>& a){os << '{';for(int i=0;i<sz(a);i++){if(i>0&&i<sz(a))os << ", ";os << a[i];}os<<'}';return os;}
template<class T> ostream& operator<<(ostream& os, const set<T>& a) {os << '{';int i=0;for(auto p:a){if(i>0&&i<sz(a))os << ", ";os << p;i++;}os << '}';return os;}
template<class T> ostream& operator<<(ostream& os, const multiset<T>& a) {os << '{';int i=0;for(auto p:a){if(i>0&&i<sz(a))os << ", ";os << p;i++;}os << '}';return os;}
template<class T1,class T2> ostream& operator<<(ostream& os, const map<T1,T2>& a) {os << '{';int i=0;for(auto p:a){if(i>0&&i<sz(a))os << ", ";os << p;i++;}os << '}';return os;}

const int mod=998244353;
int main()
{
	int n,m;
	scanf("%i %i",&n,&m);
	vector<int> b(m);
	for(int i=0;i<m;i++)
        scanf("%i",&b[i]);
    int c;
    scanf("%i",&c);
    int start=c;
    vector<int> a(n);
    for(int i=1;i<=n;i++)
        a[i-1]=i;
    for(int i=0;i<=n-m;i++)
    {
        for(int j=0;j<m;j++)
        {
            a[i+b[j]-1]=a[i+j];
        }
    }
    int ans=0;
    for(auto p:a)
    {
        ans=(ans+(ll)p*c)%mod;
        //printf("%i\n",ans);
        c=(ll)c*start%mod;
    }
    printf("%i\n",ans);
    /*cout << "Brute force: \n" << a << endl;
    vector<int> jednom(m);
    for(int i=1;i<=m;i++)
        jednom[i-1]=i;
    for(int j=0;j<m;j++)
        jednom[b[j]-1]=jednom[j];
    cout << jednom << endl;
    if(start==-1)
    {
        printf("NEMA!\n");
        return 0;
    }
    while(cycle.front()!=start)
    {
        cycle.pb(cycle.front());
        cycle.pop_front();
    }
    vector<int> krug;
    for(auto p:cycle)
        krug.pb(p);
    cout << krug;*/
    return 0;
}