1003124005

Find the value of a parameter $a\in \mathbb{R}$ so that the point $C=[2;0;6]$ lies on the straight line $p$ defined by the parametric equations $$\begin{array}{rl}p:x& =-1+m,\\ y& =a+m,\\ z& =3+m;m\in \mathbb{R}.\end{array}$$