Online

package online;
import java.util.Scanner;
public class Online
{
    public static void main(String[] args)
    {
        int m,n,o;
        Scanner input = new Scanner (System.in);
        m=input.nextInt();
        n=input.nextInt();
        o=input.nextInt();
        Triangle ob=new Triangle();
        ob.Area(1,1,1);
    }

}

public class Triangle
{
    private int side1;
    private int side2;
    private int side3;

    public void SetSide(int a,int b,int c)
    {
        this.side1=a;
        this.side2=b;
        this.side3=c;
    }
    public boolean IsValid()
    {
        if(this.side1+this.side2>this.side3)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
    public int[] GetSide()
    {
        int[] b={this.side1,this.side2,this.side3};
        return b;
    }

    Triangle()
    {
        /*
        this.side1=1;
        this.side2=1;
        this.side3=1;
        */
    }
    Triangle(int x,int y,int z)
    {
        this.side1=x;
        this.side2=y;
        this.side3=z;
    }
    public double Area(int a,int b)
    {
        return 0.5*a*b;
    }
    public double Area(int a,int b,int c)
    {
        float d=(a+b+c)/2;
        float e=d*(d-a)*(d-b)*(d-c);
        double f=Math.sqrt(e);
        return f;
    }

    public double Area(int a,int b,double c)
    {
        double f=Math.sin(c);
        double d=0.5*a*b*f;
        return d;
    }

    public double Area(int x1,int y1,int x2,int y2,int x3,int y3)
    {
        double r1=x2-x1;
        double k1=y2-y1;
        double s1=Math.pow(r1,2);
        double s2=Math.pow(k1,2);
        double p=s1+s2;
        double l1=Math.sqrt(p);

        double r2=x2-x3;
        double k2=y2-y3;
        double s3=Math.pow(r2,2);
        double s4=Math.pow(k2,2);
        double p1=s3+s4;
        double l2=Math.sqrt(p1);

        double r3=x1-x3;
        double k3=y1-y3;
        double s5=Math.pow(r3,2);
        double s6=Math.pow(k3,2);
        double p2=s5+s6;
        double l3=Math.sqrt(p2);

        double l=(l1+l2+l3)/2;

        double g=l*(l-l1)*(l-l2)*(l-l3);

        double k=Math.sqrt(g);

        return k;
    }
}