#include<stdio.h>
#include<cmath>

int min(int a,int b)
{
	return a<=b?a:b;
}
int max(int a,int b)
{
	return a>=b?a:b;
}
int main()
{
	int l,temx,x1,y1,x2,y2,x3,y3;
	double area,girth,a,b,c,n,temy;

	while(scanf("%d%d%d%d%d%d",&x1,&y1,&x2,&y2,&x3,&y3)&&(x1||y1||x2||y2||x3||y3))
	{
		a=sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
		b=sqrt((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3));
		c=sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1));
		girth=(a+b+c)/2;
		area=sqrt(girth*(girth-a)*(girth-b)*(girth-c));
		
		l=0;
		if(x1!=x2) {
			for(temx=min(x1,x2);temx<=max(x1,x2);temx++)
			{
				temy=y1-(x1-temx)*(1.0*(y1-y2)/(x1-x2));
				if(floor(temy)==ceil(temy)) l++;
			}
		}
		else l=l+abs(y2-y1)+1;

		if(x3!=x2) {
			for(temx=min(x3,x2);temx<=max(x3,x2);temx++)
			{
				temy=y3-(x3-temx)*(1.0*(y3-y2)/(x3-x2));
				if(floor(temy)==ceil(temy)) l++;
			}
			l-=1;
		}
		else l=l+abs(y2-y3);

		if(x1!=x3) {
			for(temx=min(x1,x3);temx<=max(x1,x3);temx++)
			{
				temy=y1-(x1-temx)*(1.0*(y1-y3)/(x1-x3));
				if(floor(temy)==ceil(temy)) l++;
			}
			l-=2;
		}
		else l=l+abs(y3-y1)-1;

		n=area-l/2+1;
		printf("%.0lf\n",floor(n));
	}
	return 0;
}



/*0 0 1 0 0 1
0 0 5 0 0 5
*/
			

• 本来就没有必要用海轮公式算面积。 (0) sza 2006-08-13 19:58:58