using System;

public class Program

{

    public static double f(double x)

    {

        return 2 * Math.Sqrt(1-x*x);

    }

    public static void Main()

    {

        int n=50;

        double a=-1, b=1;

        double suma=0;

        for (int i=0; i<n; i++)

        {

            suma +=(f(a+i*(b-a)/n)+f(a+(i+1)*(b-a)/n))/2*(b-a)/n;

        }

        Console.WriteLine($"El valor de la integral es: {suma}");

    }

}