import java.util.Scanner;
import java.lang.Math;

class Lesson_1011_Activity{
    public static void main(String[] args)
     {
Scanner scan = new Scanner(System.in);
System.out.println("Enter a number in base 8:");
int input = scan.nextInt();

boolean illegalDigit = false;
int temp = input;
int octalexponent = 0;
int sum = 0;

while (temp > 0)
{int digit = temp % 10;
  temp /=10;
  if (digit >7)
   illegalDigit = true;
sum += digit * Math.pow(8,octalexponent);
octalexponent++;

}

if (input > 77777777)
      {System.out.println("ERROR: Incorrect Octal Format");}
else if (illegalDigit == true)
{System.out.println("ERROR: Incorrect Octal Format");
}
else
{System.out.println(sum);

}

      }
    }