

int main(int argc, char* argv[])
{
	double a,b,c,d,v,s,S,PI=3.1415926;
	scanf("%lf%lf%lf%lf%lf",&a,&b,&c,&d,&v);
	s=(double)(a+b+c+d)/2;
	if((s-a)*(s-b)*(s-c)*(s-d)-a*b*c*d*cos(PI*v/360)*cos(PI*v/360)<0)
	{
		printf("Invalid input");
	}
	else
	{
	S=sqrt((s-a)*(s-b)*(s-c)*(s-d)-a*b*c*d*cos(PI*v/360)*cos(PI*v/360));
    printf("%.4lf",S);
	}
	return 0;
}
