#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) {
  while (a && b)
    if (a > b)
      a %= b;
    else
      b %= a;
  return a + b;
}
struct S {
 public:
  int first;
  int second;
  bool operator<(const struct S &_b) const {
    if (second == _b.second)
      return first > _b.first;
    else
      return second > _b.second;
  }
};
void f(char &d) {
  switch (d) {
    case 'T':
      d = '9' + 1;
      return;
    case 'J':
      d = '9' + 2;
      return;
    case 'Q':
      d = '9' + 3;
      return;
    case 'K':
      d = '9' + 4;
      return;
    case 'A':
      d = '9' + 5;
      return;
  }
}
int main() {
  int n, m, k;
  cin >> n >> m >> k;
  vector<int> mas(n);
  for (int i = 0; i < n; i++) cin >> mas[i];
  sort(mas.begin(), mas.end());
  int pool = k;
  for (int i = 0;; i++) {
    if (m <= pool) {
      cout << i << endl;
      return 0;
    }
    if (i == n) break;
    pool += mas[n - i - 1] - 1;
  }
  cout << -1 << endl;
}
