#include <bits/stdc++.h>
using namespace std;
template <typename T>
void p(T val) {}
void solve();
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int t = 1;
  while (t--) {
    solve();
    cout << "\n";
  }
  cerr << "time taken : " << (float)clock() / CLOCKS_PER_SEC << " secs" << endl;
  return 0;
}
void solve() {
  int n, m, k;
  cin >> n >> m >> k;
  vector<int> v(n);
  for (int i = 0; i < n; ++i) {
    cin >> v[i];
    v[i]--;
  }
  sort(v.begin(), v.end(), greater<int>());
  int devices = k;
  int i = 0;
  while (devices < m && i < n) {
    devices += v[i];
    i++;
  }
  if (devices >= m) {
    cout << i;
  } else
    cout << -1;
}
