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