import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class BinaryToDecimal
{
    public static void main(String args[]) throws Exception, IOException
    {
        int bin;
        int i = 0;
        int ldigit=0;
        int dcm=0;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        System.out.print("Enter Binary value: ");
        bin=Integer.parseInt(br.readLine());

        while (bin != 0)
        {
            ldigit = bin%10;   //last digit of binary no
            dcm = dcm+ldigit *((int) Math.pow(2,i));
            i++;
            bin = bin / 10;    //removimg last digit from binary no
        }
        System.out.println("The decimal value for the given binary is: "+dcm);

    }
}

 OUTPUT:

Enter Binary value: 1101
The decimal value for the given binary is:13