#include<bits/stdc++.h>
using namespace std;
double d(int x1,int x2,int y1,int y2) {
	return ((x1-x2)*(x1-x2)*(y1-y2)*(y1-y2))*((x1-x2)*(x1-x2)*(y1-y2)*(y1-y2));
}
int main() {
	int x1,y1,x2,y2,x3,y3;
	cin>>x1>>y1>>x2>>y2>>x3>>y3;
	double a,b,c,d1,e;
	a=d(x1,y1,x2,y2);
	b=d(x1,y1,x3,y3);
	c=d(x2,y2,x3,y3);
	d1=(a+b+c)/2;
	e=sqrt(d1*(d1-a)*(d1-b)*(d1-c));
	printf("%.2lf",e);
	return 0;
}

为什么会输出很奇怪的东西啊