Evaluate the following line integral along the curve C .
\[
\int_{C}(y-z) d s ; C \text { is the helix }\langle 5 \cos t, 5 \sin t, t\rangle \text {, for }-2 \pi \leq t \leq 0
\]
The value of the integral is \( \square \) .
(Type an exact answer, using radicals as needed.)