#include <bits/stdc++.h>
using namespace std;
int main() {
  int lines, devices, initialsockets;
  cin >> lines >> devices >> initialsockets;
  int linesockets[lines], sumsockets = initialsockets;
  for (int i = 0; i < lines; i++) {
    cin >> linesockets[i];
  }
  sort(linesockets, linesockets + lines);
  reverse(linesockets, linesockets + lines);
  if (devices <= initialsockets) {
    cout << 0 << endl;
    return 0;
  } else {
    for (int i = 0; i < lines; i++) {
      sumsockets += linesockets[i] - 1;
      if (sumsockets >= devices) {
        cout << i + 1 << endl;
        return 0;
      }
    }
  }
  cout << -1 << endl;
  return 0;
}
