#include <bits/stdc++.h>
using namespace std;
bool cmp(int a, int b) { return a > b; }
int main() {
  int n, m, k;
  cin >> n >> m >> k;
  int arr[n];
  for (int i = 0; i < n; i++) {
    cin >> arr[i];
  }
  if (k >= m) {
    cout << 0 << endl;
    return 0;
  }
  sort(arr, arr + n, cmp);
  int ans = 0;
  m -= k;
  for (int i = 0; i < n; i++) {
    if (m <= 0) break;
    m -= arr[i] - 1;
    ans++;
  }
  if (m > 0)
    cout << -1 << endl;
  else
    cout << ans << endl;
  return 0;
}
