#include<stdio.h> #include<math.h> int main() { int x1,y1,x2,y2,x3,y3; double s; scanf("%d %d %d %d %d %d",&x1,&y1,&x2,&y2,&x3,&y3); while(x1!=0||y1!=0||x2!=0||y2!=0||x3!=0||y3!=0) { s=0.5abs((x1-x3)(y2-y3)-(x2-x3)*(y1-y3));

printf("%.1lf\n",s); scanf("%d %d %d %d %d %d",&x1,&y1,&x2,&y2,&x3,&y3); } return 0; }