09. Area of Figures

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace areaOfDifferentShapes
{
    class Program
    {
        static void Main(string[] args)
        {
            string shape = Console.ReadLine();

            if (shape=="square")
            {
                double side = double.Parse(Console.ReadLine());
                double area = side * side;
                Console.WriteLine($"{area:F3}");
            }
            else if (shape == "rectangle")
            {
                double sideA = double.Parse(Console.ReadLine());
                double sideB = double.Parse(Console.ReadLine());
                double area = sideA * sideB;
                Console.WriteLine($"{area:f3}");
            }
            else if (shape == "circle")
            {
                double side = double.Parse(Console.ReadLine());
                double area = Math.PI * side * side;
                Console.WriteLine($"{area:f3}");
            }
            else if (shape=="triangle")
            {
                double side = double.Parse(Console.ReadLine());
                double height = double.Parse(Console.ReadLine());
                double area = (side / 2) * height;
                Console.WriteLine($"{area:f3}");

            }
        }
    }
}