#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define chmin(x,y) x = min((x),(y));
#define chmax(x,y) x = max((x),(y));
using namespace std;
using ll = long long ;
using P = pair<int,int> ;
using pll = pair<long long,long long>;
const int INF = 1e9;
const long long LINF = 1e17;
const int MOD = 1000000007;
//const int MOD = 998244353;
const double PI = 3.14159265358979323846;

int main(){
    ll n,m,p;
    cin >> n >> m >> p;
    vector<ll> a(n),maxx(61,-1);
    ll mx = 0;
    rep(i,n){
        cin >> a[i];
        chmax(mx,a[i]);
        ll b = a[i];
        ll c = 1;
        while(b%p==0){
            b /= p;
            ++c;
        }
        chmax(maxx[c],b); 
    }
    vector<ll> dp(4000,0);
    dp[0] = 1;
    for(int i=0;i<4000;i++){
        for(int j=1;j<61;j++){
            if(maxx[j]==-1) continue;
            if(i+j>=4000) break;
            chmax(dp[i+j],dp[i]*maxx[j]);
        }
        if(mx*dp[i] > m){
            cout << i+1 << endl;
            return 0;
        }
    }
    cout << -1 << endl;
    return 0;
}