PROGRAM sqrt
BEGIN

	STRING dummy := "abcde";  --This is dummy to satisfy the grammar

	FLOAT n;
	FLOAT x1,x2;
	FLOAT fx, dfx;
	FLOAT error;
	INT i;

	FUNCTION VOID main()
	BEGIN
		error := 0.001;
		READ (x1);
		fx := x1*x1 - n;
		dfx := 2.0*x1;
		x2 := x1 - fx/dfx;

		x1 := x2;
		fx := x1*x1 - n;
		dfx := 2.0*x1;
		x2 := x1 - fx/dfx;
		DO
			x1 := x2;
			fx := x1*x1 - n;
			dfx := 2.0*x1;
			x2 := x1 - fx/dfx;
		WHILE ((x1 - x2) > error);

		WRITE (x2);
	END
END