public static void main(String[] args) {	//an = a1+(n-1)*d	double pi = 0;	double flag = 1.0;	for(int i = 1;i<100000000;i++) {	pi += flag/(1+(i-1)*2);	flag=-flag;	}	System.out.println(pi);	System.out.println(pi*4.0);}