Three Dimensional Geometry

If the direction cosines \(l, \mathrm{~m}, \mathrm{n}\) of two lines are connected by relations \(l-5 \mathrm{~m}+3 \mathrm{n}=0\) and \(7 l^2+5 \mathrm{~m}^2-3 \mathrm{n}^2=0\), then value of \(l+\mathrm{m}+\mathrm{n}\) is