double s(double a,double b,double c,double d,double f);
int main()
{
	double a,b,c,d,e,f;
	scanf("%lf%lf%lf%lf%lf",&a,&b,&c,&d,&e);
	f=e*3.1415926/180;
	if(s(a,b,c,d,f)==-1)
	{
		printf("Invalid input");
	}
	else
	{
		printf("%.4lf",s(a,b,c,d,f));
	}

}
double s(double a,double b,double c,double d,double f)
{
	double p,t,m,n;
	m=f/2;
	t=(a+b+c+d)/2;
	n=(t-a)*(t-b)*(t-c)*(t-d) - a*b*c*d*cos(m)*cos(m);
	if(n>=0)
	{
		p=sqrt(n);
	    return(p);
	}
	else
	{
		return(-1);
	}
}