How many years after the Department submitted a plan to Congress to consolidate its 60-plus Washington-area offices into a single headquarters complex did the earliest DHS begin moving to St. Elizabeths?
return the  Department submitted a plan to Congress to  consolidate its 60-plus Washington-area offices into a  single headquarters complex ;return the  earliest DHS did begin moving to St. Elizabeths ;return year of #1 ;return year of #2 ;return difference of #4 and  #3
['select', 'select', 'project', 'project', 'arithmetic']