source_code: import java.io.InputStreamReader;
  import java.io.IOException;
  import java.io.OutputStreamWriter;
  import java.util.Arrays;
  import java.io.BufferedWriter;
  import java.io.BufferedReader;
  import java.io.OutputStream;
  import java.io.PrintWriter;
  import java.io.Writer;
  import java.util.StringTokenizer;
  import java.io.InputStream;
  
  /**
   * Built using CHelper plug-in
   * Actual solution is at the top
   * @author Lokesh Khandelwal
   */
  public class Main {
  	public static void main(String[] args) {
  		InputStream inputStream = System.in;
  		OutputStream outputStream = System.out;
  		InputReader in = new InputReader(inputStream);
  		OutputWriter out = new OutputWriter(outputStream);
  		TaskA solver = new TaskA();
  		solver.solve(1, in, out);
  		out.close();
  	}
  }
  
  class TaskA {
      public void solve(int testNumber, InputReader in, OutputWriter out) {
          int n=in.nextInt(),m=in.nextInt(),k=in.nextInt();
          int ans=-1;
          int i;
          int a[]=new int[n];
          for(i=0;i<n;i++)
              a[i]=in.nextInt();
          Arrays.sort(a);
          int p=k,c=0;
          for(i=n-1;i>=0;i--)
          {
              if(p>=m)
                  break;
              p+=a[i]-1;
              c++;
          }
          if(p>=m)
              out.printLine(c);
          else out.printLine(-1);
      }
  }
  
  class InputReader
  {
      BufferedReader in;
      StringTokenizer tokenizer=null;
  
      public InputReader(InputStream inputStream)
      {
          in=new BufferedReader(new InputStreamReader(inputStream));
      }
      public String next()
      {
          try{
              while (tokenizer==null||!tokenizer.hasMoreTokens())
              {
                  tokenizer=new StringTokenizer(in.readLine());
              }
              return tokenizer.nextToken();
          }
          catch (IOException e)
          {
              return null;
          }
      }
      public int nextInt()
      {
          return Integer.parseInt(next());
      }
      }
  
  class OutputWriter {
  	private final PrintWriter writer;
  
  	public OutputWriter(OutputStream outputStream) {
  		writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
  	}
  
  	public OutputWriter(Writer writer) {
  		this.writer = new PrintWriter(writer);
  	}
  
  	public void print(Object...objects) {
  		for (int i = 0; i < objects.length; i++) {
  			if (i != 0)
  				writer.print(' ');
  			writer.print(objects[i]);
  		}
  	}
  
  	public void printLine(Object...objects) {
  		print(objects);
  		writer.println();
  	}
  
  	public void close() {
  		writer.close();
  	}
  }
  
  