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