Where is the error in the code of exclusions?

Question

C++ / C#

Write a C# program that calculates the value of an expression using the for statement. It is forbidden to use the functions of the
Math class. Compare the calculated values ​​of the expression with the values ​​obtained using the check function.

Algorithm

code

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

namespace Lab_08
{
    class Program
    {
        static void Main(string[] args)
        {
        L:
            Console.Write("x=");
            double x = double.Parse(Console.ReadLine());
            if (x <= -1 || x >= 1)
            {
                Console.WriteLine("Значення х не входить в промiжок вiд -1 до 1. Введiть ще раз"); goto L;
            }
            else
                Console.Write("n=");
            int n = int.Parse(Console.ReadLine());
            double s = 1, c = 1;
            for (int i = 1; i <= n; i++)
            {
                double v = 1;
                for (double j = n - i + 1; i <= n; i++)
                {
                    v = v * j;
                }
                c = c * x;
                double f = 1;
                for (int k = 1; k <= n; k++) f = f * k; 
                s = s + c * v / f;
            }
            double o = Math.Pow(1+x, n);
            if (Math.Abs(s - o) < 1e-6)
            {
                Console.WriteLine("Результат: " + s);
            }
            Console.ReadLine();
        }
    }
}