import java.util.Scanner;

              class BinaryToD
              {
              int binaryToDecimal(String binaryString)
              {
              int decimal = 0;
              int binaryLength = binaryString.length();
              for(int i = 0; i < binaryLength; i++)
              
              {
              char binaryDigit = binaryString.charAt(i);
              if(binaryDigit != '0' && binaryDigit != '1')
              {
              System.out.println("Invalid Binary Input !!");
              return -1;
              }
              int power = binaryLength - 1 - i;
              int digit = binaryDigit == '1' ? 1 : 0;
              decimal += digit * Math.pow(2, power);
              }
              return decimal;
              }
              void binaryToDecimal()
              {
              System.out.println(" ");
              System.out.println("Program to convert binary number to decimal number");
              Scanner scan = new Scanner(System.in);
              System.out.print("Enter a binary number : ");
              String binaryString = scan.nextLine();
              int decimal = binaryToDecimal(binaryString);
              if(decimal != -1){
              System.out.println("Decimal Number is : " + decimal);
              }
              }
              public static void main(String args[])
              {
              BinaryToD b = new BinaryToD();
              b.binaryToDecimal();
              }
              }