#include #include typedef long long int ll; using namespace std; typedef pair P; using namespace atcoder; template using min_priority_queue = priority_queue, greater>; #define USE998244353 #ifdef USE998244353 const ll MOD = 998244353; // const double PI = 3.141592653589; using mint = modint998244353; #else const ll MOD = 1000000007; using mint = modint1000000007; #endif const int MAX = 20000001; long long fac[MAX], finv[MAX], inv[MAX]; void COMinit() { fac[0] = fac[1] = 1; finv[0] = finv[1] = 1; inv[1] = 1; for (int i = 2; i < MAX; i++){ fac[i] = fac[i - 1] * i % MOD; inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD; finv[i] = finv[i - 1] * inv[i] % MOD; } } long long COM(int n, int k){ if (n < k) return 0; if (n < 0 || k < 0) return 0; return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD; } ll gcd(ll x, ll y) { if (y == 0) return x; else if (y > x) { return gcd (y, x); } else return gcd(x % y, y); } ll lcm(ll x, ll y) { return x / gcd(x, y) * y; } ll my_sqrt(ll x) { // ll m = 0; ll M = 3000000001; while (M - m > 1) { ll now = (M + m) / 2; if (now * now <= x) { m = now; } else { M = now; } } return m; } ll keta(ll num, ll arity) { ll ret = 0; while (num) { num /= arity; ret++; } return ret; } ll ceil(ll n, ll m) { // n > 0, m > 0 ll ret = n / m; if (n % m) ret++; return ret; } ll pow_ll(ll x, ll n) { if (n == 0) return 1; if (n % 2) { return pow_ll(x, n - 1) * x; } else { ll tmp = pow_ll(x, n / 2); return tmp * tmp; } } vector compress(vector& v) { // [3 5 5 6 1 1 10 1] -> [1 2 2 3 0 0 4 0] vector u = v; sort(u.begin(), u.end()); u.erase(unique(u.begin(),u.end()),u.end()); map mp; for (int i = 0; i < u.size(); i++) { mp[u[i]] = i; } for (int i = 0; i < v.size(); i++) { v[i] = mp[v[i]]; } return v; } vector Eratosthenes( const ll N ) { vector is_prime( N + 1 ); for( ll i = 0; i <= N; i++ ) { is_prime[ i ] = true; } vector P; for( ll i = 2; i <= N; i++ ) { if( is_prime[ i ] ) { for( ll j = 2 * i; j <= N; j += i ) { is_prime[ j ] = false; } P.emplace_back( i ); } } return P; } int main() { ll n, m, a, b; cin >> n >> m >> a >> b; vector c(m); for (int i = 0; i < m; i++) { cin >> c[i]; } sort(c.begin(), c.end()); // (k, *) のとき (ck, k) (ck, *) にするには、コスト b + a(c - 1) vector divisor; for (ll i = 1; i * i <= n; i++) { if (i * i == n) divisor.push_back(i); else if (n % i == 0) { divisor.push_back(i); divisor.push_back(n / i); } } sort(divisor.begin(), divisor.end()); int d = divisor.size(); vector dp(d, (ll)1e18); // cost of divisor[d] dp[0] = 0; min_priority_queue> que; que.push({0, 0}); while (que.size()) { // 最大 auto p = que.top(); que.pop(); // cout << p.first << ' ' << divisor[p.second] << '\n'; int id = p.second; ll NG_m = (ll)1e18; for (int i = 0; i < m; i++) { if (c[i] % divisor[id] == 0) { NG_m = c[i]; break; } } for (int i = id + 1; i < d; i++) { if (divisor[i] % divisor[id]) continue; if (divisor[i] >= NG_m) break; ll C = divisor[i] / divisor[id]; ll cst = b + a * (C - 1); if (dp[i] > dp[id] + cst) { dp[i] = dp[id] + cst; que.push({dp[i], i}); } } } if (dp[d - 1] == (ll)1e18) { cout << -1 << endl; } else { cout << dp[d - 1] - b << '\n'; } return 0; }