#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <iomanip>
#include <numeric>
#include <queue>
#include <stack>
using namespace std;
using ll = long long;
void chmin(ll& a, ll b) {
	a = min(a, b);
}
int main() {
	ll N;int M;ll A, B;
	cin >> N >> M >> A >> B;
	vector<ll> C(M);
	for (int i = 0;i < M;i++) cin >> C[i];
	vector<ll> D;
	for (ll x = 1;x*x <= N;x++) {
		if (N%x != 0) continue;
		D.push_back(x);
		D.push_back(N/x);
	}
	sort(D.begin(),D.end());
	D.erase(unique(D.begin(),D.end()), D.end());
	int L = D.size();
	ll inf = (1LL << 60);
	vector<ll> dp(L, inf);
	dp[0] = 0;
	for (int i = 0;i < L;i++) {
		if (dp[i] == inf) continue;
		ll now = D[i];
		ll mn = inf;
		for (auto t : C) {
			if (t%now == 0) mn = min(mn, t);
		}
		for (int j = i+1;j < L;j++) {
			ll nx = D[j];
			if (nx%now != 0) continue;
			if (mn <= nx) continue;
			ll c = nx / now;
			ll cst = (A * (c - 1)) + (i == 0 ? 0 : B);
			chmin(dp[j], dp[i] + cst);
		}
	}
	cout << (dp.back() == inf ? -1 : dp.back()) << endl;
}