#include <bits/stdc++.h>
using namespace std;
const int MAXN = 60;
int a[MAXN];
int main() {
  int n, m, k;
  cin >> n >> m >> k;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  sort(a + 1, a + n + 1);
  if (k == 0 and m != 0) {
    cout << -1;
    return 0;
  }
  int cnt = k;
  int p = 0;
  for (int i = n; i >= 1; i--) {
    if (cnt >= m) {
      cout << p;
      return 0;
    } else {
      cnt += a[i];
      cnt--;
      p++;
    }
  }
  if (cnt >= m) {
    cout << p;
    return 0;
  }
  cout << -1;
}
