#include <bits/stdc++.h>

using i64 = long long;
constexpr i64 inf = 1ll << 50;

int main() {
    i64 N, A, B; int M; std::cin >> N >> M >> A >> B;
    std::vector<i64> C(M); for (auto &e : C) std::cin >> e;
    std::sort(C.begin(), C.end());

    std::map<i64, i64> dp;
    std::map<i64, i64> mi_d;

    auto calc_mi_d = [&](const i64 x) {
        if (mi_d.find(x) != mi_d.end()) return;
        for (const auto e : C) {
            if (e % x == 0) {
                mi_d[x] = e;
                return;
            }
        }
        mi_d[x] = inf;
        return;
    };

    auto solve = [&](auto &&self, const i64 x) -> i64 {
        calc_mi_d(x);
        if (std::binary_search(C.begin(), C.end(), x)) return inf;
        if (x == 1) return 0;
        if (dp.find(x) != dp.end()) return dp[x];

        std::vector<i64> dvs;
        for (i64 i = 1; i * i <= x; ++i) {
            if (x % i == 0) {
                dvs.push_back(i);
                dvs.push_back(x / i);
            }
        }

        i64 result = inf;
        for (const auto e : dvs) {
            if (e == x) continue;
            i64 val = self(self, e) + A * (x / e - 1);
            if (mi_d[e] <= x) continue;
            result = std::min(result, val);
        }
        return dp[x] = result + B;
    };

    const auto ans = solve(solve, N);
    std::cout << (ans >= inf ? -1 : ans - B) << std::endl;
}