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