Number of compounds with one lone pair of electrons on central atom amongst following is _____________.
\( \mathrm{O_3} \), \( \mathrm{H_2O} \), \( \mathrm{SF_4} \), \( \mathrm{ClF_3} \), \( \mathrm{NH_3} \), \( \mathrm{BrF_5} \), \( \mathrm{XeF_4} \)