#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k;
  cin >> n >> m >> k;
  vector<int> a;
  for (int i = 0; i < n; i++) {
    int b;
    cin >> b;
    a.push_back(b);
  }
  int min = 0;
  int total = k;
  if (m <= k) {
    cout << min;
    return 0;
  }
  sort(a.begin(), a.end());
  for (int i = a.size() - 1; i >= 0; i--) {
    total += a[i] - 1;
    min++;
    if (total >= m) {
      cout << min;
      return 0;
    }
  }
  cout << -1;
  return 0;
}
