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