/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2022.08.13 09:43:32
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;


template<typename T>
struct Dijkstra {
private:
    int V;
    struct edge { int to; T cost; };
    vector<vector<edge>> G;
public:
    const T inf = numeric_limits<T>::max();

    vector<T> d; 

    Dijkstra() {}
    Dijkstra(int V) : V(V) {
        G.resize(V);
    }

    Dijkstra<T>& operator=(const Dijkstra<T>& obj) {
        this->V = obj.V;
        this->G = obj.G;
        this->d = obj.d;
        return *this;
    }

    void add_edge(int from, int to, T weight, bool directed = false) {
        G[from].push_back({to,weight});
        if (!directed) G[to].push_back({from,weight});
    }

    int add_vertex() {
        G.push_back(vector<edge>());
        return V++;
    }

    void build(int s) {
        d.assign(V, inf); 
        typedef tuple<T, int> P; 
        priority_queue<P, vector<P>, greater<P>> pq;
        d[s] = 0; 
        pq.push(P(d[s], s)); 
        while (!pq.empty()) {
            P p = pq.top(); pq.pop();
            int v = get<1>(p);
            if (d[v] < get<0>(p)) continue; 
            for (const edge &e : G[v])
            {
                if (d[e.to] > d[v] + e.cost) {
                    d[e.to] = d[v] + e.cost;
                    pq.push(P(d[e.to], e.to));
                }
            }
        }
    }
};

template<typename T>
vector<T> enum_div(T n) {
    vector<T> ret;
    for (T i = 1; i * i <= n; ++i)
    {
        if (n % i == 0)
        {
            ret.push_back(i);
            if (i * i != n)
            {
                ret.push_back(n / i);
            }
        }
    }
    return ret;
}

int main() {
    int n,m;
    ll a,b;cin >> n >> m >> a >> b;
    vector<int> c(m);
    for (int i = 0; i < m; i++) {
        cin >> c[i];
    }
    auto v = enum_div(n);
    sort(v.begin(), v.end());
    Dijkstra<ll> g(v.size());
    for (int i = 1; i < v.size(); i++) {
        bool ok = true;
        for (int j = 0; j < m; j++) {
            if (c[j]%v[0]==0 && c[j] <= v[i]) {
                ok = false;
                break;
            }
        }
        if (!ok) continue;
        g.add_edge(0,i,a*(v[i]-1),true);
    }
    for (int i = 1; i < v.size()-1; i++) {
        for (int j = i+1; j < v.size(); j++) {
            if (v[j] % v[i] != 0) continue;
            bool ok = true;
            for (int k = 0; k < m; k++) {
                if (c[k]%v[i]==0 && c[k] <= v[j]) {
                    ok = false;
                    break;
                }
            }
            if (!ok) continue;
            g.add_edge(i,j,a*(v[j]/v[i]-1)+b,true);
        }
    }
    g.build(0);
    if (g.d[v.size()-1] == g.inf) {
        cout << -1 << endl;
    }
    else {
        cout << g.d[v.size()-1] << endl;
    }
    return 0;
}