#include <bits/stdc++.h>
using namespace std;
long long pow(long long n, long long m) {
  if (m == 0) return 1;
  long long x = pow(n, m / 2);
  if (m % 2 == 0)
    return (x * x) % 1000000007;
  else
    return (((x * x) % 1000000007) * n) % 1000000007;
}
void input(string n) {}
void output() {}
int main() {
  input("2");
  ios::sync_with_stdio(false);
  int n, m, k;
  cin >> n >> m >> k;
  vector<int> a;
  a.push_back(k);
  for (int i = 0; i < n; i++) {
    int tmp;
    cin >> tmp;
    a.push_back(tmp);
  }
  sort(a.begin() + 1, a.end());
  reverse(a.begin() + 1, a.end());
  int dev = m;
  int count = 1;
  for (int i = 0; i < a.size(); i++) {
    if (dev <= a[i]) {
      dev = 0;
      break;
    } else {
      dev -= (a[i] - 1);
      count++;
    }
  }
  if (dev)
    cout << -1 << endl;
  else
    cout << count - 1 << endl;
}
