using System;

public class Program

{

    public static void Main()

    {

        int first;

        int second;

        int third;

        double area;

        float semiperimeter;

        Console.WriteLine("What is the length of the first side");

        first = int.Parse(Console.ReadLine());

        Console.WriteLine("What is the length of the second side");

        second = int.Parse(Console.ReadLine());

        Console.WriteLine("What is the length of the third side");

        third = int.Parse(Console.ReadLine());

        semiperimeter = (first + second + third) / 2;

        area = Math.Sqrt(semiperimeter * (first - semiperimeter) * (second - semiperimeter) * (third - semiperimeter));

        Console.WriteLine("The area of the triangle is {0}" ,area);

    }

}