#include<bits/stdc++.h>
using namespace std;
int x1,x2,x3,y1,y2,y3,a,h;
double s;
int main()
{
	cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
	a = x2 - x1;
	h = y3 - y2;
	s = a * h / 2;
	cout << s;
	return 0;
}

为什么CE？？？