#include <bits/stdc++.h>
using namespace std;
int n, m, k, a[50], counter;
int main() {
  cin >> n >> m >> k;
  for (int i = 0; i < n; i++) {
    scanf("%d", &a[i]);
  }
  sort(a, a + n);
  for (int i = n - 1; i >= 0; i--) {
    if (k >= m) {
      cout << counter;
      return 0;
    }
    counter++;
    k += a[i];
    k--;
  }
  if (k >= m) {
    cout << counter;
    return 0;
  } else
    puts("-1");
  return 0;
}
