Let a plane P contain two lines
$$ \overrightarrow{\mathrm{r}}=\hat{\mathrm{i}}+\lambda(\hat{\mathrm{i}}+\hat{\mathrm{j}}), \lambda \in \mathrm{R} \text { and } \overrightarrow{\mathrm{r}}=-\hat{\mathrm{i}}+\mu(\hat{\mathrm{j}}-\hat{\mathrm{k}}), \mu \in \mathrm{R} $$ If $\mathrm{Q}(\alpha, \beta, \gamma)$ is the foot of the perpendicular drawn from the point $\mathrm{M}(1,0,1)$ to P , then $3(\alpha+\beta+\gamma)$ equals $\_\_\_\_$ .