using System;

public class Program

{

    public static void Main(string[] args)

    {

        Console.WriteLine("x = ");

        double x = double.Parse(Console.ReadLine());

        double y;

        if (x >= 0)

        {

            y = 7 * x;

        }

        else

        {

            y = 3.5 * x;

        }

        Console.WriteLine("y = " + y);

        Console.ReadKey();

    }

}