#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <cmath>

static const int MOD = 1000000007;
using ll = long long;
using u32 = unsigned;
using u64 = unsigned long long;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max() / 32 * 15 + 208;

template <class T, class U>
vector<T> make_v(U size, const T& init){ return vector<T>(static_cast<size_t>(size), init); }

template<class... Ts, class U>
auto make_v(U size, Ts... rest) { return vector<decltype(make_v(rest...))>(static_cast<size_t>(size), make_v(rest...)); }

template<class T> void chmin(T &a, const T &b){ a = (a < b ? a : b); }
template<class T> void chmax(T &a, const T &b){ a = (a > b ? a : b); }

int main() {
    int n, m, p;
    cin >> n >> m >> p;
    vector<int> a(n);
    vector<int> b(n);
    for (auto &&i : a) scanf("%d", &i);
    int X = 0;
    int maxx = *max_element(a.begin(),a.end());
    if(maxx > m) {
        cout << 1 << "\n";
        return 0;
    }
    for (int i = 0; i < n; ++i) {
        while(a[i]%p == 0) {
            a[i] /= p;
            b[i]++;
        }
        X = max(X, b[i]);
    }
    auto x = *max_element(a.begin(),a.end());
    if(x == 1) {
        puts("-1");
        return 0;
    }
    vector<int> mx(X+1, 0);
    for (int i = 0; i < n; ++i) {
        chmax(mx[b[i]], a[i]);
    }
    vector<int> mae(X+1, 0);
    for (int i = 0; i <= X; ++i) {
        if(mx[i] == 0) continue;
        mae[i] = mx[i];
        for (int j = 0; j < X; ++j) {
            mae[i] *= p;
        }
    }
    vector<ll> dp(10000, 1);
    int ans = INF<int>;
    for (int i = 0; i < 10000; ++i) {
        if(dp[i] > m){
            cout << i << "\n";
            return 0;
        }
        if(dp[i]*maxx > m){
            cout << i+1 << "\n";
            return 0;
        }
        for (int j = 0; j <= X; ++j) {
            chmax(dp[i+j+1], dp[i]*mx[j]);
        }
    }
    return 0;
}