public class Sqrt
{
	public static void main(String args[]){
		System.out.println( sqrt( 2.0 ) );
		System.out.println( Math.sqrt(2.0) );
	}

	static double sqrt( double a ){
		double x=1.0;
		do{
			x = ( x + a/x ) /2;
		}while( Math.abs(x*x-a)/a > 1e-6 );
		return x;
	}
}