public class Triangle
{
    private int a, b, c;

    public Triangle(int a, int b, int c)
    {
	this.a = a;
	this.b = b;
	this.c = c;
    }

    public boolean estIsocele()
    {
	return (a == b || a == c || c == b);
    }

    public boolean estEquilateral()
    {
	return (a == b && b == c);
    }

    public boolean estRectangle()
    {
	double ac = Math.pow(a, 2);
	double bc = Math.pow(b, 2);
	double cc = Math.pow(c, 2);

	return ( (ac + bc == cc) ||
		 (ac + cc == bc) ||
		 (bc + cc == ac)
		 );
    }

    public boolean estScalen()
    {
	return (! estRectangle() &&
		! estIsocele());
    }

    public double surface()
    {
	double p = (a + b + c) / 2.0;
	double surf = Math.sqrt(p * (p - a) * (p - b) * (p - c));
	
	return surf;
    }

}