#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);
    int amax = 0;
    vector<int> nums(40, -1);
    for(int i = 0; i < n; ++i){
        cin >> a[i];
        chmax(amax, a[i]);
        int X = a[i], cnt = 0;
        while(X % p == 0){
            X /= p;
            cnt += 1;
        }
        chmax(nums[cnt], X);
    }

    vector<ll> dp(10001);
    dp[0] = 1;
    for(int i = 0; i < 10000; ++i){
        if(dp[i] == 0)  continue;
        if(dp[i] * amax > m){
            cout << i + 1 << endl;
            return 0;
        }
        for(int j = 0; j < 40; ++j){
            if(nums[j] == -1)   continue;
            if(i + j + 1 > 10000)   continue;
            chmax(dp[i + j + 1], dp[i] * nums[j]);
        }
    }
    
    cout << -1 << endl;

    return 0;
}