
int main()
{
 double a,b,c,d,e,i;
 scanf("%lf\n%lf\n%lf\n%lf\n%lf",&a,&b,&c,&d,&e);
 e=e/180*3.1415926;
 i=(a+b+c+d)/2;
 if((i-a)*(i-b)*(i-c)*(i-d)-a*b*c*d*cos(e/2)*cos(e/2)>=0)
 printf("%.4lf",sqrt((i-a)*(i-b)*(i-c)*(i-d)-a*b*c*d*cos(e/2)*cos(e/2)));
 else
	 printf("Invalid input");
 return 0;

}