using System;

public class Program

{

    public static void Main()

    {

        string s ;

        double a, b ,c , perimetrs , laukums ;

        Console.WriteLine("Ievadiet malu a");

        s = Console.ReadLine () ;

        a = double.Parse(s);

        Console.WriteLine("Ievadiet malu b");

        s = Console.ReadLine () ;

        b = double.Parse(s);

        Console.WriteLine("Ievadiet malu c");

        s = Console.ReadLine () ;

        c = double.Parse(s);

        Console.WriteLine("Ievadiet malu perimetrs");

        s = Console.ReadLine () ;

        perimetrs = double.Parse(s);

        perimetrs = a+b+c ;

        Console.WriteLine("Atbilde"+ perimetrs);

            Console.WriteLine("Ievadiet malu perimetrs");

        s = Console.ReadLine () ;

        perimetrs = double.Parse(s);

        laukums = Math.Sqrt (perimetrs*(perimetrs-a)*(perimetrs-b)*(perimetrs-c )) ; 

        Console.WriteLine("Atbilde" + laukums ) ;

        Console.ReadKey();

    }

}