AreaOfFigures

using System;
    class AreaOfFigures
    {
        static void Main()
        {
            string figure = Console.ReadLine();
            string figure1 = figure.ToLower();
            if (figure1=="square")
            {
                var square = double.Parse(Console.ReadLine());
                var area = square * square;
                Console.WriteLine(Math.Round(area,3));
            }
            else if (figure1=="rectangle")
            {
                var a = double.Parse(Console.ReadLine());
                var b = double.Parse(Console.ReadLine());
                var area = a * b;
                Console.WriteLine(Math.Round(area, 3));

            }
            else if (figure1 == "circle")
            {
                var r = double.Parse(Console.ReadLine());
                var area = Math.PI * r * r;
                Console.WriteLine(Math.Round(area, 3));

            }
            else if (figure1 == "triangle")
            {
                var c = double.Parse(Console.ReadLine());
                var h = double.Parse(Console.ReadLine());
                var area = (c * h) / 2;
                Console.WriteLine(Math.Round(area, 3));

            }
        }
    }