// #define _GLIBCXX_DEBUG
#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,b) for(int i=0;i<b;i++)
#define rrep(i,b) for(int i=b-1;i>=0;i--)
#define rep1(i,b) for(int i=1;i<b;i++)
#define repx(i,x,b) for(int i=x;i<b;i++)
#define rrepx(i,x,b) for(int i=b-1;i>=x;i--)
#define fore(i,a) for(auto i:a)
#define fore1(i,a) for(auto &i:a)
#define rng(x) (x).begin(), (x).end()
#define rrng(x) (x).rbegin(), (x).rend()
#define sz(x) ((int)(x).size())
#define pb push_back
#define fi first
#define se second

using namespace std;
using namespace atcoder;

using ll = long long;
using ld = long double;
template<typename T> using mpq = priority_queue<T, vector<T>, greater<T>>;
template<typename T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<typename T> bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<typename T> ll sumv(const vector<T>&a){ll res(0);for(auto&&x:a)res+=x;return res;}
bool yn(bool a) { if(a) {cout << "Yes" << endl; return 1;} else {cout << "No" << endl; return 0;}}
#define dame { cout << "No" << endl; return 0;}
#define dame1 { cout << -1 << endl; return 0;}
#define test(x) cout << "test" << x << endl;
#define deb(x,y) cout << x << " " << y << endl;
#define debp(p) cout << p.fi << " " << p.se << endl;
#define deb3(x,y,z) cout << x << " " << y << " " << z << endl;
#define deb4(x,y,z,x2) cout << x << " " << y << " " << z << " " << x2 << endl;
#define out cout << ans << endl;
#define outd cout << fixed << setprecision(20) << ans << endl;
#define outm cout << ans.val() << endl;
#define outv fore(yans , ans) cout << yans << "\n";
#define outdv fore(yans , ans) cout << yans.val() << "\n";
#define show(x) cerr<<#x<<" = "<<x<<endl;
#define showv(v) {fore(vy , v) {cout << vy << " ";} cout << endl;}
#define showv2(v) fore(vy , v) cout << vy << "\n";
using pll = pair<ll,ll>;
using pil = pair<int,ll>;
using pli = pair<ll,int>;
using pii = pair<int,int>;
using pdd = pair<ld,ld>;
using tp = tuple<int ,int ,int>;
using vi = vector<int>;
using vd = vector<ld>;
using vl = vector<ll>;
using vs = vector<string>;
using vb = vector<bool>;
using vpii = vector<pii>;
using vpli = vector<pli>;
using vpll = vector<pll>;
using vpil = vector<pil>;
using vvi = vector<vector<int>>;
using vvl = vector<vector<ll>>;
using vvs = vector<vector<string>>;
using vvb = vector<vector<bool>>;
using vvpii = vector<vector<pii>>;
using vvpli = vector<vector<pli>>;
using vvpll = vector<vpll>;
using vvpil = vector<vpil>;
using mint = modint998244353;
using vm = vector<mint>;
using vvm = vector<vector<mint>>;
vector<int> dx={1,0,-1,0,1,1,-1,-1},dy={0,1,0,-1,1,-1,1,-1};
ll gcd(ll a, ll b) { return a?gcd(b%a,a):b;}
ll lcm(ll a, ll b) { return a/gcd(a,b)*b;}
const double eps = 1e-10;
const ll LINF = 1001002003004005006ll;
const int INF = 1001001001;

struct math_lib{
    vvl div,mul;

    void div_init(int n){
        div.resize(n+1);
        mul.resize(n+1);

        for(ll i = 1;i <= n;i++){
            for(ll j = i;j <= n;j+=i){
                div[j].pb(i);
                mul[i].pb(j);
            }
        }

        return;
    }

    vl divisor(ll x){
        vl res;
        for(ll i=1;i*i<=x;i++){
            if (x%i != 0) continue;
            res.pb(i);
            if (i*i != x) res.pb(x/i); 
        }
        sort(rng(res));
    
        return res;
    }

    ll sqrt(ll x) {
        ll l = 0, r = ll(2e9)+1;
        while (l+1<r) {
          ll c = (l+r)/2;
          if (c*c <= x) l = c; else r = c;
        }
        return l;
    }

    ll logx(ll x,int a){
        ll tmp=1;
        ll ret=0;

        while(tmp <= x){
            if (tmp >= LLONG_MAX/a) break;
            tmp *= a;
            ret++;
        }
        ret--;

        return ret;
    }

    ll pow(ll x , ll a){

        assert(x > 0);
        assert(a >= 0);

        ll ret = 1;

        rep(_,a){
            assert (ret < LLONG_MAX/x);
            ret *= x;
        }

        return ret;
    }

    ll base(ll x,int a){
        ll ans=0,y;
        for (ll i=0;x>0;i++){
            y = x/a;
            ans += (x - y*a)*pow(10,i);
            x = y;
        }
        return ans;
    }

    string baseS(ll x,int a){
        string ans;
        ll y;
        for (ll i=0;x>0;i++){
            y = x/a;
            ans += '0' + (x - y*a);
            x = y;
        }
        reverse(rng(ans));
        return ans;
    }
} math;

// .div.mul : div[i]、mul[i]はそれぞれiの約数、倍数を格納している。
// .div_init(n) : div,mulを初期化。引数はnまで。n < 1e6 ~ 1e7。
// .divisor(x) : xの約数列挙。xは64bit整数。
// .sqrt(x) : floor(sqrt(x))。xは64bit整数。誤差は発生しない。
// .logx(x , a) : floor(loga(x))。xは64bit整数。誤差は発生しない。
// .pow(x , a) : x^a。誤差は発生しない。
// .base(x , a) : x(10進数)をa進数表記に。1 <= a <= 10。戻り値はll型。 
// .baseS(x , a) : x(10進数)をa進数表記に。1 <= a <= 10。戻り値はstring型。 

struct edge{
    int from,to;
    ll cost;

    edge(int from_=0,int to_=0,ll cost_=0) : from(from_),to(to_),cost(cost_) {}
};

int main(){
    ll n,m,a,b; cin>>n>>m>>a>>b;
    vl c(m);
    rep(i,m) cin>>c[i];

    vl v = math.divisor(n);

    int k = sz(v);

    vl low(k);

    rep(i,k){
        ll tmp = LINF;
        rep(j,m){
            if (c[j] % v[i] == 0) chmin(tmp , c[j] / v[i]);
        }
        low[i] = tmp;
    }

    // test(1);

    vector<vector<edge>> e(k);

    rep(i,k){
        repx(j,i+1,k){
            if (v[j] % v[i] != 0) continue;

            ll cost = 0;
            if (i != 0) cost = b;

            cost += (a) * ((v[j] / v[i]) - 1);

            if ((v[j]/v[i]) >= low[i]) cost = LINF;


            if (cost == LINF) continue;
            e[i].pb(edge(i,j,cost));
            // deb(i,j);
            // deb(v[i],v[j]);
            // show(cost);
        }
    }

    // test(1);

    vector<ll> dist(k,LINF);
    mpq<pli> q;
    
    int st = 0;
    dist[st] = 0;
    q.push({dist[st] , st});
    
    while(!q.empty()){
        pli p = q.top();
        q.pop();
        ll dist_dum = p.first;
        int from = p.second;
    
        if (dist[from] < dist_dum) continue;
    
        fore(ey , e[from]){
            int to = ey.to;
            ll cost = ey.cost;
    
            if (chmin(dist[to] , dist_dum + cost)){
                q.push({dist[to] , to});
            }
        }
    }

    if (dist[k-1] == LINF) dame1;

    cout << dist[k-1] << endl;

// 消せ！！！！！！　#define _GLIBCXX_DEBUG
// priority_queue でしぬ

    return 0;
}