Vectors in Space · Superchallenge problem

A particle moves under the constant force $\mathbf F = (2, -1, 3)$. It first travels along the helix $\mathbf r(t) = \left(\cos t, \sin t, \dfrac{t}{\pi}\right)$ from $t = 0$ to $t = 3\pi$, and then in a straight line to the point $(4, 0, 1)$. Find the total work done by $\mathbf F$.