import java.util.Random;
import java.util.Scanner;

class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		Random ran = new Random();
		int N = sc.nextInt();
		int K = sc.nextInt();
		int x = 0;
		int y = 0;
		while(x < N){
				x = sc.nextInt();
				
				if((N-1)%(K+1) == (x-1)%(K+1))y++;
				else y = 0;
				
				if(y == 5){
					System.out.println(N);
					break;
				}
				
				x += ran.nextInt(K)+1;
			}
			System.out.println(x);
		}
	}