// Problem:
// The value of pi can be determined by the series equation:

//  pi = 4(1-1/3+1/5-1/7+1/9-1/11+...)
// Write a program to approximate the value of pi using the formula given including terms up through 1/99.


public class taylorpi{
    static double estimate=0.0;
    static double max_int=99.0;
    static String factor_sign = "+";
    public static void setFactorials(){
        double i = 1.0;
        while(i <= taylorpi.max_int){
            if(taylorpi.factor_sign == "+"){
                taylorpi.estimate += (1.0/i);
                i+=2;
                taylorpi.factor_sign = "-";

            }else if(taylorpi.factor_sign == "-"){
                taylorpi.estimate -= (1.0/i);
                i+=2;
                taylorpi.factor_sign = "+";
            }
        }
    }
    public static void main(String[] args){
        taylorpi.setFactorials();
        taylorpi.estimate *= 4;
        System.out.println(taylorpi.estimate);
    }
}