double num = Math.sin(Math.PI);
        long a = (long)num;
        if (a == num){
            System.out.println("true 1   " + num + "    " + a);
            //return Long.toString(a);
        }

        else {
                System.out.println("false 1  " + num + "   " + a);
                long n = Double.toString(num).length() - Long.toString(a).length() - 1;
                if (n < 14) num = Math.round(num * Math.pow(10, n))/Math.pow(10, n);
                else num = Math.round(num * Math.pow(10, 14))/Math.pow(10, 14);

                a = (long)num;  // tranh TH sau khi bien doi lai ve so nguyen VD (Tan(pi/4))

                if (a == num)
                    System.out.println("true 2   " + num + "   " + a);
                else System.out.println("false 2   " + num + "   " + a);
        }