A hexagon A B C D E F has A B=18 \mathrm{~cm}, B C=8 \mathrm{~cm}, C D=10 \mathrm{~cm}, D E=15 \mathrm{~cm}, E F=20 \mathrm{~cm}, F A=1 \mathrm{~cm}, \angle F A B=90^{\circ}, \angle C D E=90^{\circ} and B C is parallel to E F. Determine the area of this hexagon, in \mathrm{cm}^{2}.