#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, a[105], m, c;
  cin >> n >> m >> c;
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  for (int i = n; i >= 0; i--) {
    if (c >= m) {
      cout << n - i;
      goto barra;
    }
    c += a[i - 1] - 1;
  }
  cout << -1;
barra:;
}
