source_code: import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.Arrays;
  import java.util.StringTokenizer;
  
  public class Main {
  	public static void main(String[] args) throws IOException {
  		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  		String[] in = br.readLine().split(" ");
  		
  		int n=Integer.parseInt(in[0]),m=Integer.parseInt(in[1]),k=Integer.parseInt(in[2]);
  		
  		StringTokenizer st = new StringTokenizer(br.readLine());
  		int[] caps = new int[n];
  		for (int i = 0; i < caps.length; i++) {
  			caps[i] = Integer.parseInt(st.nextToken());
  		}
  		Arrays.sort(caps);
  		
  		int curSockets=k, neededLines=0;
  		int i = n-1;
  		while(curSockets<m && i>=0){
  			curSockets+=caps[i]-1;
  			neededLines++;
  			i--;
  		}
  		if(curSockets>=m)
  			System.out.println(neededLines);
  		else
  			System.out.println(-1);
  	}
  }
  