#include <bits/stdc++.h>

#define rep(i, a, b) for(int i = (a); i <= (b); i ++)
using std::cin, std::cout, std::cerr;
using ll = long long;

void Solve() {
    int n, m, p; cin >> n >> m >> p;
    std::vector<int> a(n);
    rep(i, 0, n - 1) cin >> a[i];

    const int k = 1000, t = 30 + 1;
    std::vector<ll> f(k + 1, 1);
    std::vector<int> b(t + 1, 1);
    for(int x : a) {
        int c = 0;
        while(x % p == 0) {
            x /= p;
            c ++;
        }
        b[c + 1] = std::max(b[c + 1], x);
    }
    rep(i, 0, k) rep(j, 0, t) {
        if(i + j <= k) {
            f[i + j] = std::max(f[i + j], f[i] * b[j]);
            f[i + j] = std::min(f[i + j], ll(1e9));
        }
    }

    bool ok = false;
    int ans = 1e9;
    int max = *std::max_element(a.begin(), a.end());
    rep(i, 0, k) if(f[i] * max > m) {
        ok = true;
        ans = std::min(ans, i + 1);
    }
    cout << (ok ? ans : -1) << '\n';
}

int main() {
    std::ios::sync_with_stdio(false);
    int T = 1;
    while(T --) {
        Solve();
    }
}