#include<iostream>
#include<array>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<tuple>
#include<cassert>
using namespace std;
typedef long long ll;
typedef unsigned int ui;
const ll mod = 1000000007;
const ll INF = (ll)1000000007 * 1000000007;
typedef pair<int, int> P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define Per(i,sta,n) for(int i=n-1;i>=sta;i--)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef long double ld;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<ll, ll> LP;
int dx[4]={1,-1,0,0};
int dy[4]={0,0,1,-1};
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;}

int n,v=32,MAX=2000;
ll m,p;

ll a[35];
ll dp[35][2010];


void solve(){
    cin >> n >> m >> p;
    rep(i,n){
        ll b;cin >> b;int s=0;
        while(b%p==0){
            s++;
            b/=p;
        }
        chmax(a[s],b);
    }
    rep(i,v+1) rep(j,MAX) dp[i][j]=0;
    dp[0][0]=1;
    rep(i,v){
        //cout << i << " " << a[i] << endl;
        rep(j,MAX){
            if(j>=i){
                if(dp[i+1][j-i]*a[i]>m){
                    dp[i+1][j]=m+1;
                }
                else dp[i+1][j]=max(dp[i+1][j-i-1]*a[i],dp[i][j]);
            }
            else dp[i+1][j]=dp[i][j];
            //cout << i+1 << " " << j << " " << dp[i+1][j] << endl;
        }
    }
    ll B=1;
    rep(i,v){
        ll s=a[i];rep(j,i) s*=p;
        chmax(B,s);
    }
    //cout << B << endl;
    int ans=mod;
    rep(i,MAX){
        //cout << i << " " << dp[v][i] << endl;
        if(dp[v][i]>m) chmin(ans,i);
        else if(dp[v][i]*B>m) chmin(ans,i+1); 
    }
    if(ans<mod)cout << ans << endl;
    else cout << -1 << endl;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(50);
    solve();
}