import javax.swing.JOptionPane;


class prob2 {
	public static void main(String[] args) {
		double side1 = Integer.parseInt(JOptionPane.showInputDialog(null,"Triangle side 1: "));
		double side2 = Integer.parseInt(JOptionPane.showInputDialog(null,"Triangle side 2: "));
		double side3 = Integer.parseInt(JOptionPane.showInputDialog(null,"Triangle side 3: "));
		boolean bools = isValid(side1,side2,side3);
		if (bools == false) {
			JOptionPane.showMessageDialog(null,"Sides don't work.  Sorry.");
		}
		else {
			JOptionPane.showMessageDialog(null,"Area is " + area(side1,side2,side3));
		}
		
	}
	
	public static boolean isValid(double a, double b, double c) {
		boolean possible = ( ( (a + b) > c ) && ( (a + c) > b ) &&
			      ( (b + c ) > a ) ) ; 
		return possible;
	}
	
	public static double area(double a, double b, double c) {
		double s = 0.5 * (a+b+c);
		s = Math.sqrt(s*(s-a)*(s-b)*(s-c));
		return s;
	}
}