#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < n; i++)
#define rep2(i, x, n) for(int i = x; i <= n; i++)
#define rep3(i, x, n) for(int i = x; i >= n; i--)
#define each(e, v) for(auto &e: v)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)x.size()
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
const int MOD = 1000000007;
//const int MOD = 998244353;
const int inf = (1<<30)-1;
const ll INF = (1LL<<60)-1;
template<typename T> bool chmax(T &x, const T &y) {return (x < y)? (x = y, true) : false;};
template<typename T> bool chmin(T &x, const T &y) {return (x > y)? (x = y, true) : false;};

struct io_setup{
    io_setup(){
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout << fixed << setprecision(15);
    }
} io_setup;

int main(){
    int N;
    ll M, P;
    cin >> N >> M >> P;
    vector<ll> a(N);
    rep(i, N) cin >> a[i];
    vector<int> k(N, 0);

    vector<ll> m(50, 1), b(50, 1);
    rep(i, N){
        ll memo = a[i];
        while(memo%P == 0) {memo /= P, k[i]++;}
        if(chmax(b[k[i]], a[i])) m[k[i]] = memo;
    }

    vector<ll> dp(10000, 1);
    int ans = inf;
    rep(i, 10000){
        rep(j, 50){
            if(i-j-1 >= 0){
                chmax(dp[i], dp[i-j-1]*m[j]);
            }
        }
        if(dp[i] > M){
            chmin(ans, i);
            break;
        }
        rep(j, 50){
            if(dp[i]*b[j] > M) chmin(ans, i+1);
        }
    }

    cout << (ans == inf? -1 : ans) << '\n';
}