/*source */

import java.lang.Math;
public class MathTest{
    public double area(double i){
        return Math.PI*i*i;
    }	
    public static void main(String[] args){
    	double a = 6;
    	MathTest mt = new MathTest();
        System.out.println("area="+mt.area(a));
        System.out.println("E="+Math.E);
    }
    
}


/*result */
--------------------Configuration: <Default>--------------------
area=113.09733552923255
E=2.718281828459045

Process completed.