#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <tuple>
#include <cmath>
#include <numeric>
#include <functional>
#include <cassert>

#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

using namespace std;
typedef long long ll;

template<typename T>
vector<vector<T>> vec2d(int n, int m, T v){
    return vector<vector<T>>(n, vector<T>(m, v));
}

template<typename T>
vector<vector<vector<T>>> vec3d(int n, int m, int k, T v){
    return vector<vector<vector<T>>>(n, vector<vector<T>>(m, vector<T>(k, v)));
}

template<typename T>
void print_vector(vector<T> v, char delimiter=' '){
    if(v.empty()) {
        cout << endl;
        return;
    }
    for(int i = 0; i+1 < v.size(); i++) cout << v[i] << delimiter;
    cout << v.back() << endl;
}

vector<ll> list_divs(ll n){
    vector<ll> ans;
    for(int x = 1; x*x <= n; x++){
        if(n%x == 0){
            ans.push_back(x);
            if(x*x != n) ans.push_back(n/x);
        }
    }
    sort(ans.begin(), ans.end());
    return ans;
}

const ll inf = 1e18;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    ll n, m, a, b; cin >> n >> m >> a >> b;
    vector<ll> c(m);
    for(int i = 0; i < m; i++) cin >> c[i];
    auto divs = list_divs(n);
    int sz = divs.size();
    vector<ll> mn(sz, inf);
    for(int i = 0; i < sz; i++){
        ll x = divs[i];
        for(ll y: c){
            if(y%x == 0) chmin(mn[i], y);
        }
    }
    vector<ll> dp(sz, inf);
    dp[0] = 0;
    for(int i = 0; i < sz; i++){
        ll x = divs[i];
        for(int j = i+1; j < sz; j++){
            ll y = divs[j];
            if(y%x != 0) continue;
            if(y >= mn[i]) continue;
            ll tmp = dp[i] + (y/x-1)*a+b;
            chmin(dp[j], tmp);
        }
    }
    if(dp.back() == inf){
        cout << -1 << endl;
    }else{
        cout << dp.back()-b << endl;
    }
}