#include <stdio.h> #include <math.h>

double calculateTriangleArea(double x1, double y1, double x2, double y2, double x3, double y3) { double area = 0.5 * fabs((x1 - x3) * (y2 - y1) - (x1 - x2) * (y3 - y1)); return area; }

int main() { double x1, y1, x2, y2, x3, y3; scanf("%lf %lf %lf %lf %lf %lf", &x1, &y1, &x2, &y2, &x3, &y3);

double area = calculateTriangleArea(x1, y1, x2, y2, x3, y3); 
printf("%.2lf\n", area); 
return 0;

}