Compute the line integral of the scalar function
$f(x, y, z) = 1x - 3y + z^2$
along the piecewise path $C = C_1 \cup C_2$, where:
C1 is the line segment from the point (0, 0, 0) to the point (1, 1, 1).
C2 is the line segment from the point (1, 1, 1) to the point (2, 1, 2).
$\int_C f(x, y, z) ds = \Box$
