#include <stdio.h>
#include <math.h>
int main()

{
    float a, b, c, d, e, f, area;

    printf("Enter the value of a\n");
    scanf("%f", &a);

    printf("Enter the value of b\n");
    scanf("%f", &b);

    printf("Enter the value of c\n");
    scanf("%f", &c);

    printf("Enter the value of d\n");
    scanf("%f", &d);

    printf("Enter the value of e\n");
    scanf("%f", &e);

    printf("Enter the value of f\n");
    scanf("%f", &f);


    area = (a*(e-f)+b*(f-d)+c*(d-e))/2;

    printf("area is %f", area);

    return (0);
}