Three vectors $\vec{A} = a\hat{i} + \hat{j} + \hat{k}$, $\vec{B} = \hat{i} + b\hat{j} + \hat{k}$ and $\vec{C} = \hat{i} + \hat{j} + c\hat{k}$ are mutually perpendicular. The respective values of $a$, $b$ and $c$ are