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

int main ()
{
    double x1, y1, x2, y2, x3, y3;
    double s, a, b, c, area;
    
    printf("A: ");
    scanf("%lf%lf", &x1, &y1);
    printf("B: ");
    scanf("%lf%lf", &x2, &y2);
    printf("C: ");
    scanf("%lf%lf", &x3, &y3);
    
    a = sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3));
    b = sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1));
    c = sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
    s = (a + b + c) / 2;
    area = sqrt(s*(s-a)*(s-b)*(s-c));
    printf("Area is %lf\n", area);

    area = x1 * (y2 - y3);
    area += x2 * (y3 - y1);
    area += x3 * (y1 - y2);
    area /= 2;
    area = fabs(area);
    printf("Area is %lf\n", area);

    return 0;
}