#include <bits/stdc++.h>
#include <variant>

#define rep2(i,k,n) for(i64 i=(i64)(k);i<(i64)(n);i++)
#define rep(i,n) rep2(i,0,n)
#define all(x) begin(x),end(x)
#ifdef ENV_LOCAL
#define dump if (1) cerr
#else
#define dump if (0) cerr
#endif

using namespace std;
using namespace std::string_literals;

using i32 = int32_t;
using i64 = int64_t;
using f64 = double;
using f80 = long double;
using vi32 = vector<i32>;
using vi64 = vector<i64>;

//using namespace harudake;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  i32 n,m,p;
  cin>>n>>m>>p;
  vi32 a(n);
  rep(i,n)cin>>a[i];
  if (m == 1) {
    cout << 0 << endl;
    return 0;
  }
  i32 mx = *max_element(all(a));
  if (mx >= m) {
    cout << 1 << endl;
    return 0;
  }
  vi32 ra = a;
  vi32 ip(n, 1);
  rep(i,n) {
    while (ra[i] % p == 0) {
      ra[i] /= p;
      ++ip[i];
    }
  }
  vi64 dp(931, 0);
  dp[0] = 1;
  rep(i,n) {
    rep(j,901) {
      dp[j+ip[i]] = max(dp[j+ip[i]], min<i64>(m, dp[j] * ra[i]));
    }
  }
  rep(i,900) {
    if (dp[i] * mx > m) {
      cout << i+1 << endl;
      return 0;
    }
  }
  cout<<-1<<endl;
  return 0;
}