import java.util.Arrays;
import java.util.Random;

public class binarySearch { // start class
	
	// initialize the array with number 2, 4, 6 ... 2N
	public static int [] init (int N){
		int[] a;
		a = new int[N];
		for (int i = 0; i < N; i++) {
			a[i] = (2*(i+1));
		}
		return a;
	}
	
	// binary search, fill it in yourself
	public static int binarySearch(int[] a, int key, int min, int max){
		if (min > max){
			return -1;
		}
		else{
			int mid = (max + min) /2;
			System.out.println(mid);
			if (a[mid] < key) 
				return binarySearch (a, key, mid+1, max);
			else if (a[mid] > key)
				return binarySearch (a, key, 0, mid-1);
			else if (max == min);
				return min;
		}
		
	}
	
	
	
    public static void main(String[] args) {
        int n = Integer.parseInt(args[0]); // take a user input of the array size
        int key = Integer.parseInt(args[1]);
        int a[] = init (n);
        System.out.println(Arrays.toString(a));
        System.out.println(binarySearch(a, key, 0, a.length-1));
    }
	
	
}