//---------------------------------------------------------------------------------
vector<vector<Point>> PAN::mergecontours(vector<vector<Point>> contours){
vector<vector<Point>> contourCOG;
getcenter(contours, contourCOG);
contours._Pop_back_n(contours.size());//empty contours and push merged contours into it
for (unsigned int i = 0; i < contourCOG.size(); i++){
float field = contourCOG[i][0].y;
vector<int> matchindex = findnear(contourCOG, field, INLINE_Y, 0.30);
if (matchindex.size() <=1){
vector<Point> temp;
temp.push_back(Point(contourCOG[i][1].x - BUFFER, contourCOG[i][1].y - BUFFER));
temp.push_back(Point(contourCOG[i][2].x + BUFFER, contourCOG[i][2].y + BUFFER));
if (temp[0].x < 0){ temp[0].x = 0; }
if (temp[0].y < 0){ temp[0].y = 0; }
if (temp[1].x > panimage.x_right){ temp[1].x = panimage.x_right; }
if (temp[1].y > panimage.y_lower){ temp[1].y = panimage.y_lower; }
//please check boundary conditions
contours.push_back(temp);
}
else{
int minx = contourCOG[i][2].x, maxx = contourCOG[i][1].x, miny = contourCOG[i][2].y, maxy = contourCOG[i][1].y;
Point finalCOG;
//merging begins
unsigned int j;
for (j=0; j < matchindex.size(); j++){
if (contourCOG[matchindex[j]][1].x < minx){ minx = contourCOG[matchindex[j]][1].x; }
if (contourCOG[matchindex[j]][1].y < miny){ miny = contourCOG[matchindex[j]][1].y; }
if (contourCOG[matchindex[j]][2].x > maxx){ maxx = contourCOG[matchindex[j]][2].x; }
if (contourCOG[matchindex[j]][2].y > maxy){ maxy = contourCOG[matchindex[j]][2].y; }
}
vector<Point> temp;
temp.push_back(Point(minx , miny));
temp.push_back(Point(maxx, maxy));
if (temp[0].x < 0){ temp[0].x = 0; }
if (temp[0].y < 0){ temp[0].y = 0; }
if (temp[1].x > panimage.x_right){ temp[1].x = panimage.x_right; }
if (temp[1].y > panimage.y_lower){ temp[1].y=panimage.y_lower; }
finalCOG = Point((temp[0].x + temp[1].x) / 2, (temp[0].y + temp[1].y) / 2);
if (isrepeat(contours,finalCOG)){ contours.push_back(temp); }
}
}
return contours;
}
int main(){
int i,j,k,l,test,t=1;
// freopen("in.txt","r",stdin);
point a,b,c;
while(scanf("%lf %lf",&a.x,&a.y)==2){
scanf("%lf %lf %lf %lf",&b.x,&b.y,&c.x,&c.y);
point cen=getcenter(a,b,c);
double r=dist(a,cen);
double ans=(double)2.0*r*pi;
printf("%.2lf\n",ans);
}
return 0;
}