import java.io.*;
import java.lang.*;

public class  BinaryToHexa{
	public static void main(String[] args)throws IOException{
		BufferedReader bf= new BufferedReader(new InputStreamReader(System.in));
	    System.out.println("Enter the Binary number:");
		String hex = bf.readLine();
		long num = Long.parseLong(hex);
		long rem;
		while(num > 0){
			rem = num % 10;
			num = num / 10;
			if(rem != 0 && rem != 1){
				System.out.println("This is not a binary number.");
				System.out.println("Please try once again.");
				System.exit(0);
			}
		}
		int i= Integer.parseInt(hex,2);
		String hexString = Integer.toHexString(i);
		System.out.println("Hexa decimal: " + hexString);
	}
}