#include <bits/stdc++.h>
using namespace std;

const long long INF = 1E18 + 7;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m, a, b; cin >> n >> m >> a >> b;
    vector<int> c(m);
    for (int i = 0; i < m; i++) {
        cin >> c[i];
    }
    vector<int> div;
    for (int i = 1; i * i <= n; i++) {
        if (n % i == 0) {
            div.push_back(i);
            if (n / i != i) {
                div.push_back(n / i);
            }
        }
    }
    sort(div.begin(), div.end());
    int d = div.size();
    vector<long long> dst(d, INF);
    long long ans = INF;
    dst[0] = 0;
    for (int i = 0; i < d; i++) {
        int max_div = n + 1;
        for (int v : c) {
            if (v % div[i] == 0) {
                max_div = min(max_div, v);
            }
        }
        if (max_div > n) {
            ans = min(ans, dst[i] + 1LL * (n / div[i] - 1) * a);
        }
        for (int j = i + 1; j < d; j++) {
            if (div[j] < max_div && div[j] % div[i] == 0) {
                dst[j] = min(dst[j], dst[i] + b + 1LL * (div[j] / div[i] - 1) * a);
            }
        }
    }
    cout << (ans == INF ? -1 : ans);
}