using System;

namespace FindPi
{
    class Program
    {
        static void Main(string[] args)
        {
            double pi = 4; //Create the variable for Pi and set its start value to 4.
            int denominator = 3; //The variable for the denominator in the Pi formula.
            int counter = 3; //Where are we in Pi.
            int termNumber = 2; //Keep track of the term number to display to the user.

            ///Next chunk of code asks the user how many terms they want.
            Console.WriteLine("Please enter the number of terms:");
            string termsNumberString = Console.ReadLine();
            int termsNumber;
            termsNumber = Convert.ToInt32(termsNumberString);
            termsNumber = termsNumber * 2;

            ///Display the table headers.
            string titleCol1 = ("Term");
            string titleCol2 = ("Pi");
            string formatTitleTable = "{0,-15} {1,-10}";
            Console.WriteLine(formatTitleTable, titleCol1, titleCol2);

            ///Displaying the first term. This is done maually rather than using the formula because it's a starting point.
            string term1Col1 = ("1");
            string term1Col2 = ("4.0000000000000000");
            string formatTerm1Table = "{0,-15} {1,-10}";
            Console.WriteLine(formatTerm1Table, term1Col1, term1Col2);

            ///Figuring out the term value for Pi.
            while (denominator <= termsNumber)
            {
                if (counter % 2 != 0)
                {
                    pi -= Convert.ToDouble(4) / denominator;
                    counter++;
                }
                else
                {
                    pi += Convert.ToDouble(4) / denominator;
                    counter++;
                }
                denominator += 2;

                ///Displaying the term number and the value of Pi to the user in a table format.
                string col1 = ("" + termNumber);
                termNumber++;
                string col2 = ("" + pi);
                string formatTable = "{0,-15} {1,-10}";
                Console.WriteLine(formatTable, col1, col2);
            }

        }
    }
}