> #include<iostream>
> #include<math.h>
> #include<iomanip>
> using namespace std;
> 
> int main()
> {
>     double x1,y1,a,x2,y2,b,c,s,A,B,area;
>     while(cin>>x1>>y1>>a>>x2>>y2>>b)
>     {
>         if(a<b)c=a,a=b,b=c;
>         c=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
>         if(c>=a+b){area=0;goto out;}//&Iacute;&acirc;&Agrave;&euml;&raquo;??&Iuml;??&Ccedil;&ETH;
>         if(c<=a-b){area=3.1415926*b*b;goto out;}//&Auml;&Uacute;&ordm;&not;
>         A=acos((b*b+c*c-a*a)/2/b/c);//&Iuml;??&frac12;&raquo;
>         B=acos((a*a+c*c-b*b)/2/a/c);
>         s=(a+b+c)/2;
>         s=sqrt(s*(s-a)*(s-b)*(s-c));
>         area=a*a*B+b*b*A-2*s;
> out:    cout<<setiosflags(ios::fixed)<<setprecision(3)<<area<<endl;
>     }
>     return 1;
> }
>