$$ 2 \mathrm{SO}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \rightarrow 2 \mathrm{SO}_3(\mathrm{~g}) $$ The above reaction is carried out in a vessel starting with partial pressure $\mathrm{P}_{\mathrm{SO}_3}=250 \mathrm{mbar}, \mathrm{P}_{\mathrm{O}_2}=750 \mathrm{~m}$ bar and $\mathrm{P}_{\mathrm{SO}_3}=0$ bar. When the reaction is complete, the total pressure in the reaction vessel is $\_\_\_\_$ m bar. (Round off of the nearest integer).