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