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