#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<numeric>
#include<cmath>
#include<utility>
#include<tuple>
#include<cstdint>
#include<cstdio>
#include<iomanip>
#include<map>
#include<queue>
#include<set>
#include<stack>
#include<deque>
#include<unordered_map>
#include<unordered_set>
#include<bitset>
#include<chrono>
#include<random>
#include<cctype>
#include<cassert>
#include<cstddef>
#include<iterator>
#include<string_view>
#include<type_traits>

#ifdef LOCAL
#  include "debug_print.hpp"
#  define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define debug(...) (static_cast<void>(0))
#endif

using namespace std;
#define rep(i,n) for(decltype(n) i=0; i<(n); i++)
#define rrep(i,n) for(decltype(n) i=(n)-1; i>=0; i--)
#define FOR(i,a,b) for(decltype(a) i=(a); i<(b); i++)
#define RFOR(i,a,b) for(decltype(b) i=(b-1); i>=(a); i--)
#define ALL(v) v.begin(), v.end()
#define RALL(v) v.rbegin(), v.rend()
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );
#define pb push_back
using ll = long long;
using D = double;
using LD = long double;
using P = pair<int, int>;
template<typename T> using PQ = priority_queue<T,vector<T>>;
template<typename T> using minPQ = priority_queue<T, vector<T>, greater<T>>;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
void yesno(bool flag) {cout << (flag?"Yes":"No") << "\n";}

template<typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
    os << p.first << " " << p.second;
    return os;
}
template<typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &p) {
    is >> p.first >> p.second;
    return is;
}

template<typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    int s = (int)v.size();
    for (int i = 0; i < s; i++) os << (i ? " " : "") << v[i];
    return os;
}
template<typename T>
istream &operator>>(istream &is, vector<T> &v) {
    for (auto &x : v) is >> x;
    return is;
}
void in() {}
template<typename T, class... U>
void in(T &t, U &...u) {
    cin >> t;
    in(u...);
}
void out() { cout << "\n"; }
template<typename T, class... U, char sep = ' '>
void out(const T &t, const U &...u) {
    cout << t;
    if (sizeof...(u)) cout << sep;
    out(u...);
}
void outr() {}
template<typename T, class... U, char sep = ' '>
void outr(const T &t, const U &...u) {
    cout << t;
    outr(u...);
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    ll n,m,p; in(n,m,p); m++;
    vector<ll> a(n); in(a);
    vector<ll> q(n),r(n);
    rep(i,n){
        ll tmp = a[i];
        while(tmp % p == 0){
            tmp /= p;
            q[i]++;
        }
        r[i] = tmp;
    }
    if(accumulate(ALL(r),0LL) == n){
        out("-1");
        return 0;
    }
    vector<int> qr(30, -1);
    rep(i,n){
        if(qr[q[i]] == -1) qr[q[i]] = i;
        else if(r[qr[q[i]]] < r[i]) qr[q[i]] = i;
    }
    vector<ll> na,nq,nr;
    rep(i,30){
        if(qr[i] != -1){
            na.pb(a[i]);
            nq.pb(q[i]);
            nr.pb(r[i]);
        }
    }
    map<ll,ll> mp;
    auto f = [&] (auto &&self, ll x) -> ll{
        if(mp.count(x)) return mp[x];
        ll res = 1e9;
        rep(i,na.size()){
            if(x * na[i] >= m) {
                return mp[x] = 1;
            }
            else{
                if(nr[i] == 1) continue;
                chmin(res, self(self, x*nr[i] ) + nq[i] + 1);
            }
        }
        return mp[x] = res;
    };

    out(f(f,1));
}