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

int main() {

  ios::sync_with_stdio(false);
  cin.tie(0);
  long long n,m,p;
  cin >> n >> m >> p;
  vector<long long> a(n);
  vector<long long> cost(n);
  vector<long long> mul(n);
  long long amax,rmax;
  amax = 1;
  rmax = 1;
  for (int i=0;i<n;i++) {
    cin >> a[i];
    long long tmp = a[i];
    amax = max(amax,tmp);
    while (tmp%p == 0) {
      tmp /= p;
      cost[i]++;
    }
    mul[i] = tmp; 
    rmax = max(rmax,mul[i]);
  }
  vector<long long> coss(32,0);
  for (int i=0;i<n;i++) {
    long long ncos = cost[i]+1;
    coss[ncos] = max(coss[ncos],mul[i]);
  }
  vector<long long> dp(1024,0);
  dp[0] = 1;
  for (int i=0;i<1024;i++) {
    if (i == 1023) {
      cout << -1 << endl;
      break;
    }
    if (dp[i]*amax > m) {
      cout << i+1 << endl;
      break;
    }
    for (int j=1;j<32;j++) {
      if (i+j >= 1024) break;
      dp[i+j] = max(dp[i+j],dp[i]*coss[j]);
    }
  }
}