#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k, x, filter(0);
  cin >> n >> m >> k;
  int arr[n];
  for (x = 0; x < n; x++) {
    cin >> arr[x];
  }
  sort(arr, arr + n, greater<int>());
  x = k;
  while (filter < n && x < m) {
    x += arr[filter] - 1;
    filter++;
  }
  cout << (x >= m ? filter : -1);
  return 0;
}
