C#: Convert an octal number into binary

using System;  // Importing necessary namespace

public class Exercise54  // Declaration of the Exercise54 class
{  
    public static void Main()  // Main method, entry point of the program
    {
        int n1, n5, p = 1;  // Declaration of variables
        int dec = 0, i = 1, j, d;
        int binno = 0;
	
        Console.Write("\n\n");
        Console.Write("Convert Octal to Binary:\n");
        Console.Write("--------------------------");
        Console.Write("\n\n");

        Console.Write("Input an octal number (using digit 0 - 7) :");
        n1 = Convert.ToInt32(Console.ReadLine());  // Taking user input for an octal number
        n5 = n1;  // Storing the original octal number for display at the end

        // Converting the octal number to its decimal equivalent
        for (j = n1; j > 0; j = j / 10)
        {  
            d = j % 10;
            if (i == 1)
                p = p * 1;
            else
                p = p * 8;

            dec = dec + (d * p);
            i++;
        }

        /* Converting the obtained decimal equivalent to its binary representation */
        i = 1;
        for (j = dec; j > 0; j = j / 2)
        {
            binno = binno + (dec % 2) * i;
            i = i * 10;
            dec = dec / 2;
        }

        // Displaying the original octal number and its equivalent binary number
        Console.Write("\nThe Octal Number : {0}\nThe equivalent Binary  Number : {1} \n\n", n5, binno);
    }
}