double a[4],S,j,k=0;
int i;
const double Pi=3.1415926;
int main(void)
{
    for (i=0;i<4;i++)
    {
        scanf("%lf",&a[i]);
        k=k+a[i]/2;
        printf("\n");
    }
    scanf("%lf",&j);
    S=((k-a[0])*(k-a[1])*(k-a[2])*(k-a[3]) - a[0]*a[1]*a[2]*a[3]*cos(j/360*Pi)*cos(j/360*Pi));
    if (S>=0)
        printf("%.4f",sqrt(S));
    else
        printf("Invalid input");
return 0;
}

