#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <stack>
#include <array>
#include <list>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

int main()
{
    int n; cin>>n;
    ll m, p; cin>>m>>p;
    ll a[200020];
    for(int i=0; i<n; i++){
        cin>>a[i];
    }
    ll mx=*max_element(a, a+n);
    if(mx>m){
        cout<<1<<endl;
        return 0;
    }
    ll x[30];
    fill(x, x+30, 1);
    for(int i=0; i<n; i++){
        int c=0;
        ll b=a[i];
        while(b%p==0){
            b/=p;
            c++;
        }
        x[c]=max(x[c], b);
    }
    ll dp[1024]={};
    dp[0]=1;
    const ll MAX=1e9+7;
    for(int i=0; i<1024; i++){
        for(int j=0; i+j+1<1024 && j<30; j++){
            dp[i+j+1]=max(dp[i+j+1], min(dp[i]*x[j], MAX));
        }
    }
    for(int i=0; i<1024; i++){
        if(dp[i]>m/mx){
            cout<<i+1<<endl;
            return 0;
        }
    }
    cout<<-1<<endl;
    return 0;
}