// #include <atcoder/all>
// using namespace atcoder;
// using mint = modint1000000007;
// using mint = modint998244353;
#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)n; ++i)
#define rrep(i, n) for (int i = (int)n-1; i >= 0; --i)
using namespace std;
using ll = long long;
template<typename T>
inline bool chmax(T& a, const T& b) {
    if (a < b){
        a = b;
        return true;
    }
    return false;
}
template<typename T>
inline bool chmin(T& a, const T& b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}
/**
 * @brief 多次元 vector の作成
 * @author えびちゃん
 */
namespace detail {
    template<typename T, int N>
    auto make_vec(vector<int>& sizes, T const& x) {
        if constexpr (N == 1) {
            return vector(sizes[0], x);
        } else {
            int size = sizes[N-1];
            sizes.pop_back();
            return vector(size, make_vec<T, N-1>(sizes, x));
        }
    }
}
template<typename T, int N>
auto make_vec(int const(&sizes)[N], T const& x = T()) {
    vector<int> s(N);
    for (int i = 0; i < N; ++i) s[i] = sizes[N-i-1];
    return detail::make_vec<T, N>(s, x);
}
__attribute__((constructor))
void fast_io() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
}

int main() {
    int n, m, p;
    cin >> n >> m >> p;
    vector<int> a(n);
    for (auto& ai : a) cin >> ai;
    int mx = *max_element(a.begin(), a.end());
    if (mx > m) {
        cout << 1 << '\n';
        return 0;
    }

    vector<int> b = a;
    vector<int> cnt(n, 1);
    for (int i = 0; i < n; ++i) while (b[i] % p == 0) b[i] /= p, cnt[i]++;
    if (all_of(b.begin(), b.end(), [](int x) { return x == 1; })) {
        cout << -1 << '\n';
        return 0;
    }
    const int k = 500;
    auto dp = make_vec<ll>({k, 2}, 1);
    for (int i = 0; i < k; ++i) {
        for (int j = 0; j < n; ++j) {
            if (i + cnt[j] < k) {
                if (cnt[j] == 1) {
                    chmax(dp[i + 1][0], min<ll>(dp[i][0] * a[j], INT_MAX));
                } else {
                    chmax(dp[i + 1][1], min<ll>(dp[i][0] * a[j], INT_MAX));
                    chmax(dp[i + cnt[j]][0], min<ll>(dp[i][0] * b[j], INT_MAX));
                }
            }
        }
    }
    for (int i = 0; i < k; ++i) {
        for (int j = 0; j < 2; ++j) {
            if (dp[i][j] > m) {
                cout << i << '\n';
                return 0;
            }
        }
    }
}