#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;

	class triangle
	{
	private:
	double x1, x2, x3, y1, y2, y3, plot;
	public:
	triangle():x1(0),x2(0),x3(0),y1(0),y2(0),y3(0){}
	triangle(int a,int b, int c, int d, int e, int f) :x1(a),x2(b),x3(c),y1(d),y2(e),y3(f){}
	~triangle(){}

		void ivedimas()
		{
			cin>>x1>>x2>>x3>>y1>>y2>>y3;
		}

		double plotas()
		{
		  	plot=(1/2.)*abs((((x2-x1)*(y3-y1))-((x3-x1)*(y2-y1))));
		 	return plot;
		}

		void isvedimas()
		{
		 	cout<<plot<<endl;
		}
	};


	int main()
	{
 		triangle T[100];
		int n;
		double sum=0;
		cin>>n;
 		for (int i=0; i<n; i++)
  		{
   			 T[i].ivedimas();
   			 sum+=T[i].plotas();
 		 }

 	if(sum!=0)
	cout<<setprecision(3)<<fixed<<sum<<endl;
	else
	cout<<"NO"<<endl;
	}