#include <iostream>
#include <cmath>
using namespace std;
int main(){
	int x1,x2,x3,y1,y2,y3;
	cin>>x1>>y1>>x2>>y2>>x3>>y3;
	int a,b,c;
	a = sqrt(pow(abs(x1-x2),2)+pow(abs(y1-y2),2));
	b = sqrt(pow(abs(x2-x3),2)+pow(abs(y2-y3),2));
	c = sqrt(pow(abs(x1-x3),2)+pow(abs(y1-y3),2));
	int S,s;
	s = (a+b+c)*0.5;
	S = sqrt(s*(s-a)*(s-b)*(s-c));
	cout<<S<<endl;
	return 0;
}