Total number of ions from the following with noble gas configuration is _________. $\mathrm{Sr}^{2+}(z=38), \mathrm{Cs}^{+}(z=55), \mathrm{La}^{2+}(z=57), \mathrm{Pb}^{2+}(z=82), \mathrm{Yb}^{2+}(z=70)$ and $\mathrm{Fe}^{2+}(z=26)$