If $\overline{\mathrm{a}},\overline{\mathrm{b}},\overline{\mathrm{c}}$ are three vectors of equal magnitude and angle between each pair of vectors is $\mathrm{\pi }/3$ such that$\left|\overline{\mathrm{a}} + \overline{\mathrm{b}} + \overline{\mathrm{c} }\right|= \sqrt{6},$ then $\left|\overline{\mathrm{a}}\right|=$