The University of Massachusetts Amherst housing system is made up of six dormitory areas, two apartment areas, and one hotel. At UMass Amherst, first year students are required to live on campus. Housing is open to all full-time undergraduate students, regardless of year. Upper-class students who have continuously lived on campus during their first and sophomore years are guaranteed housing as long as they choose to live on campus. If, however, a student is admitted after their sophomore year, or moves off campus, and wants to move back onto campus, they are not guaranteed housing, but instead must go through a housing lottery, since demand outstrips supply. Building and room selection is accomplished by a complex system that takes into account building seniority as well as class year; those choosing to move from their building are subject to a lottery system, There are around 12,700 students living on-campus.