#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k, res = 0, w;
  cin >> n >> m >> k;
  int A[n];
  for (int i = 0; i < n; ++i) {
    cin >> A[i];
  }
  if (k == 0) {
    cout << -1;
    return 0;
  }
  sort(A, A + n);
  w = n - 1;
  while (m > 0 && w >= 0) {
    m -= k;
    k = 0;
    if (m > 0) {
      m -= A[w];
      m += 1;
      --w;
      ++res;
    }
  }
  if (m <= 0)
    cout << res;
  else
    cout << -1;
}
