#include <bits/stdc++.h>
using namespace std;
long long arr[101];
int main() {
  long long n, m, k;
  cin >> n >> m >> k;
  if (k >= m) {
    cout << 0;
    return 0;
  }
  for (int i = 0; i < n; i++) cin >> arr[i];
  sort(arr, arr + n);
  reverse(arr, arr + n);
  long long counter = 0;
  long long i = 0;
  long long prevk = k;
  while (m > k) {
    k--;
    k += arr[i++];
    counter++;
    if (k < m && k <= prevk) {
      cout << -1;
      return 0;
    }
    prevk = k;
  }
  cout << counter;
  return 0;
}
