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

namespace ConsoleApplication1
{
    class Program
    {
        static double[] X = new double[] {0, 2, 2, 0};
        static double[] Y = new double[] {0, 0, 2, 2};
        static int count;

        static double Qx, Qy, Zx, Zy;

        static double Snative = 0;
        static double Spieces = 0;

        static double e = 0.0001;

        static double Area3(double X1, double Y1, double X2, double Y2, double X3, double Y3) {
            double area = 0;
            double a, b, c, p;
            c = Math.Sqrt(Math.Pow(Y1 - Y2, 2) + Math.Pow(X1 - X2, 2));
            b = Math.Sqrt(Math.Pow(Y2 - Y3, 2) + Math.Pow(X2 - X3, 2));
            a = Math.Sqrt(Math.Pow(Y1 - Y3, 2) + Math.Pow(X1 - X3, 2));
            p = (a + b + c) / 2;
            area = Math.Sqrt(p * (p - a) * (p - b) * (p - c));
            return area;
        }

        static double ReadCoor(string str) {
            double result;
            Console.Write(str);
            result = double.Parse(Console.ReadLine());
            return result;
        }

        static void Sarea(double Ax, double Ay, string pname) {
            Spieces = Area3(Ax, Ay, X[0], Y[0], X[count - 1], Y[count - 1]);
            for (int i = 0; i < count - 1; i++) {
                Spieces += Area3(Ax, Ay, X[i], Y[i], X[i + 1], Y[i + 1]);
            }

            Console.WriteLine("Point {0} is {1}side", pname, ((Math.Abs(Snative - Spieces) < e) ? "in" : "out"));
        }


        static void Main(string[] args)
        {
            Console.WriteLine ("Enter coordinates of Q-point.");
            Qx = ReadCoor("X = ");
            Qy = ReadCoor("Y = ");

            Console.WriteLine("Enter coordinates of Z-point.");
            Zx = ReadCoor("X = ");
            Zy = ReadCoor("Y = ");

            count = X.Length;

            for (int i = 1; i < count-1; i++) {
                Snative += Area3(X[0], Y[0], X[i], Y[i], X[i + 1], Y[i + 1]);
            }

            Sarea(Qx, Qy, "Q");
            Sarea(Zx, Zy, "Z");

            Console.WriteLine("Done. Press any key...");
            Console.ReadKey(true);
        }
    }
}