#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
using namespace std;

using ll = long long;
using P = pair<int, int>;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m, p;
    cin >> n >> m >> p;
    vector<int> a(n), b(n), c(n, 1);
    int amax = 0, bmax = 0, cmax = 0;
    map<int, int> mp;
    for(int i = 0; i < n; ++i){
        cin >> a[i];
        chmax(amax, a[i]);
        b[i] = a[i];
        while(b[i] % p == 0){
            b[i] /= p;
            c[i] += 1;
        }
        chmax(bmax, b[i]);
        chmax(cmax, c[i]);
        chmax(mp[c[i]], b[i]);
    }

    if(amax > m){
        cout << 1 << endl;
        return 0;
    }
    if(bmax == 1){
        cout << -1 << endl;
        return 0;
    }

    int MAX = cmax * cmax;
    vector<ll> powp(MAX, 1);
    for(int i = 1; i < MAX; ++i)    powp[i] = powp[i - 1] * p;

    vector<ll> dp(MAX + 1);
    dp[0] = 1;
    int m2 = (m + amax - 1) / amax;
    int ans = INF;
    for(auto [cost, val] : mp){
        if(val == 1)    continue;
        for(int i = 0; i <= MAX - cost; ++i){
            if(dp[i] == 0)  continue;
            if(dp[i] * val * powp[max(0, cost - 1)] > m)    chmin(ans, i + 1);
            chmax(dp[i + cost], min<ll>(m2, dp[i] * val));
        }
    }
    for(int i = 0; i <= MAX; ++i){
        if(dp[i] >= m2) chmin(ans, i + 1);
    }

    for(int i = 0; i < n; ++i){
        if(b[i] == 1)   continue;
        ll prod = 1;
        int sum = 0;
        while(prod <= m){
            sum += 1;
            if(prod * amax > m){
                prod *= amax;
            }
            else if(prod * a[i] > m){
                prod *= a[i];
            }
            else{
                prod *= b[i];
                sum += c[i];
            }
        }
        chmin(ans, sum);
    }

    cout << ans << endl;

    return 0;
}