using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Enter the value for a");

        string a = Console.ReadLine();

        double.Parse(a);

        while (a=0 || a%1!=0)

        {

            Console.WriteLine("Invlaid value for a");

            string a = Console.ReadLine();

            double.Parse(a);

        }

        Console.WriteLine("Enter the value for b");

        string b = Console.ReadLine();

        double.Parse(b);

        Console.WriteLine("Enter the value for c");

        string c = Console.ReadLine();

        double.Parse(c);

    }

}