#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k, arr[52] = {0};
  cin >> n >> m >> k;
  for (int i = 0; i < n; i++) cin >> arr[i];
  sort(arr, arr + n);
  if (m <= k) {
    cout << 0 << "\n";
    return 0;
  } else {
    int cnt = 1, total = arr[n - 1] + (k - 1), i = n - 1;
    while (i >= 0) {
      if (total >= m) {
        cout << cnt;
        return 0;
      } else {
        if (k != 0) {
          i--;
          k--;
          total += arr[i];
          total -= 1;
          cnt++;
        } else {
          i--;
          total -= 1;
          cnt++;
          total += arr[i];
        }
      }
    }
  }
  cout << "-1";
}
