#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k;
  cin >> n >> m >> k;
  int arr[n];
  int i;
  for (i = 0; i < n; i++) cin >> arr[i];
  sort(arr, arr + n, greater<int>());
  i = 0;
  int sum = k;
  while (sum < m && i < n) {
    sum += arr[i] - 1;
    i++;
  }
  if (i == n && sum < m)
    printf("%d", -1);
  else
    printf("%d", i);
  return 0;
}
