When a certain amount of solid A is dissolved in $100 \mathrm{~g}$ of water at $25^{\circ} \mathrm{C}$ to make a dilute solution, the vapour pressure of the solution is reduced to one-half of that of pure water. The vapour pressure of pure water is $23.76 \,\mathrm{mmHg}$. The number of moles of solute A added is _____________. (Nearest Integer)