int main()
{

    double a,b,c,d,x,y,z;
    double s;
    scanf("%lf%lf%lf%lf%lf",&a,&b,&c,&d,&x);
    #define PI 3.1415926
	y=(double)cos(PI*x/360);
	z=(double)(a+b+c+d)/2;
	if((z-a)*(z-b)*(z-c)*(z-d)-a*b*c*d*y>=0)
	{
	    s=(double)sqrt((z-a)*(z-b)*(z-c)*(z-d)-a*b*c*d*y*y);
		printf("%.4lf",s);
	}
	else
	{
		printf("Invalid input");
	}
	return 0;
}