Number of compounds from the following with zero dipole moment is _________.

$$\mathrm{HF}, \mathrm{H}_2, \mathrm{H}_2 \mathrm{~S}, \mathrm{CO}_2, \mathrm{NH}_3, \mathrm{BF}_3, \mathrm{CH}_4, \mathrm{CHCl}_3, \mathrm{SiF}_4, \mathrm{H}_2 \mathrm{O}, \mathrm{BeF}_2$$