source_code: //package A;
  
  import java.io.IOException;
  import java.util.Arrays;
  import java.util.Scanner;
  
  public class Solution {
      public static void main(String args[]) throws IOException {
          Scanner in = new Scanner(System.in);
          int n = in.nextInt();
          int m = in.nextInt();
          int k = in.nextInt();
          int[] a = new int[n];
          for (int i = 0; i < n; ++i)
              a[i] = in.nextInt();
          Arrays.sort(a);
          
          int res = 0, p = n - 1;
          while (k < m && p >= 0) {
              ++res;
              k += a[p] - 1;
              --p;
          }
          if (k >= m)
              System.out.println(res);
          else
              System.out.println("-1");
      }
  }
  