#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<numeric>
#include<cmath>
#include<utility>
#include<tuple>
#include<cstdint>
#include<cstdio>
#include<iomanip>
#include<map>
#include<queue>
#include<set>
#include<stack>
#include<deque>
#include<unordered_map>
#include<unordered_set>
#include<bitset>
#include<chrono>
#include<random>
#include<cctype>
#include<cassert>
#include<cstddef>
#include<iterator>
#include<string_view>
#include<type_traits>

#ifdef LOCAL
#  include "debug_print.hpp"
#  define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define debug(...) (static_cast<void>(0))
#endif

using namespace std;
#define rep(i,n) for(decltype(n) i=0; i<(n); i++)
#define rrep(i,n) for(decltype(n) i=(n)-1; i>=0; i--)
#define FOR(i,a,b) for(decltype(a) i=(a); i<(b); i++)
#define RFOR(i,a,b) for(decltype(b) i=(b-1); i>=(a); i--)
#define ALL(v) v.begin(), v.end()
#define RALL(v) v.rbegin(), v.rend()
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );
#define pb push_back
using ll = long long;
using D = double;
using LD = long double;
using P = pair<ll, int>;
template<typename T> using PQ = priority_queue<T,vector<T>>;
template<typename T> using minPQ = priority_queue<T, vector<T>, greater<T>>;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
void yesno(bool flag) {cout << (flag?"Yes":"No") << "\n";}

template<typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
    os << p.first << " " << p.second;
    return os;
}
template<typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &p) {
    is >> p.first >> p.second;
    return is;
}

template<typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    int s = (int)v.size();
    for (int i = 0; i < s; i++) os << (i ? " " : "") << v[i];
    return os;
}
template<typename T>
istream &operator>>(istream &is, vector<T> &v) {
    for (auto &x : v) is >> x;
    return is;
}
void in() {}
template<typename T, class... U>
void in(T &t, U &...u) {
    cin >> t;
    in(u...);
}
void out() { cout << "\n"; }
template<typename T, class... U, char sep = ' '>
void out(const T &t, const U &...u) {
    cout << t;
    if (sizeof...(u)) cout << sep;
    out(u...);
}
void outr() {}
template<typename T, class... U, char sep = ' '>
void outr(const T &t, const U &...u) {
    cout << t;
    outr(u...);
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    const ll inf = 1e18;
    int n,m; ll a,b; in(n,m,a,b);
    vector<int> v(m); in(v);
    set<int> c(ALL(v));
    vector<int> divs;
    for(int i = 1; i*i <= n; i++){
        if(n%i == 0){
            if(!c.count(i)) divs.pb(i);
            if(i*i != n && !c.count(n/i)) divs.pb(n/i);
        }
    }
    sort(ALL(divs));
    int s = divs.size();
    vector<ll> mind(s, inf);
    rep(i,s)rep(j,m){
        if(v[j] % divs[i] == 0) chmin(mind[i], (ll)v[j]);
    }
    vector<ll> dist(s,inf);
    vector<vector<P>> ed(s);
    dist[0] = 0;
    rep(i,s){
        FOR(j,i+1,s){
            int x = divs[i], y = divs[j];
            if(y%x != 0) continue;
            int ok = (mind[i] > y);
            if(ok) {
                if(x == 1) ed[i].pb({(y-1)*a,j});
                else ed[i].pb({(y/x-1)*a + b, j});
            }
        }
    }

    minPQ<P> pq;
    pq.push({0,0});
    while(pq.size()){
        auto [nowd, pos] = pq.top(); pq.pop();
        if(nowd > dist[pos]) continue;
        for(auto [w, nxt] : ed[pos]){
            ll tmp = nowd + w;
            if(dist[nxt] > tmp){
                dist[nxt] = tmp;
                pq.push({tmp, nxt});
            }
        }
    }

    ll ans = dist.back();
    if(ans == inf) out("-1");
    else out(ans);
}