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