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