.........乱了
> import java.util.Scanner;
> 
> public class Main {
> 	public static void main(String[] args) {
> 		try {
> 			Scanner cin = new Scanner(System.in);
> 			long input=cin.nextLong();
> 			long n = 0;
> 			String str=Long.toBinaryString(input);
> 			n=str.lastIndexOf('1');
> 			long a=1;
> 			a<<=(n-1);
> 			a++;
> 			System.out.print(a);
> 		} catch (Exception e) {
> 			e.printStackTrace();
> 		}
> 	}
> }