BAEKJOON_1205

import java.io.*;
import java.util.*;


public class Main {

    public static void main(String[] args) throws IOException {
        Scanner scanner = new Scanner(System.in);

        int N = scanner.nextInt();      //리스트에 있는 점수
        int score = scanner.nextInt();   //태수 점수
        int P = scanner.nextInt();     //랭킹 리스트에 올라갈 수 있는 점수 개수

        Integer[] arr = new Integer[N];
        if(N==0){
            System.out.print(1);
            System.exit(0);
        }

        for(int i=0; i<N; i++){
            arr[i] = scanner.nextInt();
        }

        Arrays.sort(arr, Collections.reverseOrder());

        if (score <= arr[arr.length - 1] && N == P) {
            System.out.print(-1);
        }else{
            int rank =1;
            for(int i=0; i<N; i++){
                if (score < arr[i]) {
                    rank++;
                }else{
                    break;
                }
            }
            System.out.print(rank);
        }


    }
}