#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ALL(v) v.begin(), v.end()
typedef long long ll;

#include <bits/stdc++.h>
using namespace std;

ll p;
ll dp[200020][40];

pair<ll,int> f(ll x){
  int c=1;
  while(x%p==0){
    x/=p;
    c++;
  }
  return {x,c};
}

int main(){
  ll n,m;
  cin>>n>>m>>p;
  
  vector<ll> A(n);
  rep(i,n) cin>>A[i];
  
  ll ma=0;
  rep(i,n) ma=max(ma,A[i]);
  
  if(ma>m){
    cout<<1<<endl;
    return 0;
  }
  
  ll g=(m+ma-1)/ma;
  
  vector<pair<ll,int>> B(n);
  rep(i,n) B[i]=f(A[i]);
  
  ll ma1=0;
  rep(i,n) ma1=max(ma1,B[i].first);
  
  if(ma1<2){
    cout<<-1<<endl;
    return 0;
  }
  
  rep(i,n) dp[i][1]=A[i];
  for(int j=2;j<40;j++){
    rep(i,n){
      if(j-B[i].second>=0 && (j-1)%B[i].second==0){
        dp[i][j]=dp[i][j-B[i].second]*B[i].first;
        if(dp[i][j]>g){
          cout<<j<<endl;
          return 0;
        }
      }
    }
  }
  cout<<-1<<endl;

  return 0;
}