#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, s;
  cin >> n >> d >> s;
  vector<int> v(n);
  for (int i = 0; i < n; i++) cin >> v[i];
  sort(v.begin(), v.end());
  int c = s, f = 0, l = n - 1, k = 0;
  while (1) {
    if (c >= d) {
      f = 1;
      break;
    }
    if (l < 0) {
      f = 2;
      break;
    }
    c += v[l--] - 1;
    k++;
  }
  if (f == 2)
    cout << "-1" << endl;
  else
    cout << k << endl;
  return 0;
}
